Days of Future Past

A setting in which societies with futuristic technology have reverted to patterns from earlier time periods (e.g., medieval Europe, feudal Japan, nineteenth-century America) while remaining at a futuristic technological level (e.g., starships, Humongous Mecha, Energy Weapons). This can be either the result of relating historical metaphors to a future society, or an excuse to do a period piece IN SPACE.

This may also be an attempt to market a fantasy story as Science Fiction during a period where the latter is considered more fashionable. Just add Applied Phlebotinum which would pretty much be magic if not for the Techno Babble explaining it away as advanced science or Psychic Powers.

There are many variations on this trope (mainly because it makes making the Fantasy Counterpart Cultures easier), but most can be broken down into just a few categories:
 * 1) Feudal Future: In the future, human society will resemble a cross between medieval and early modern Europe, possibly with elements of Imperial Rome, Imperial China, and feudal Japan. Expect The Empire, although it will likely have elements of The Kingdom. Humanity may be united, in which case the parallel is to the Roman or British Empire and you can expect the ruler of humanity to be titled appropriately, or it may have been united in the past and is now descending into barbarism, in which case the parallel is with medieval Europe. Aliens are unlikely, but if present they will probably be a Fantasy Counterpart Culture for the Mongol Horde.
 * 2) Space Samurai: Future society resembles feudal Japan. Found as the local equivalent of Feudal Future in Japanese-produced work, as well as making occasional guest appearances as a stock Fantasy Counterpart Culture in Feudal Future settings.
 * 3) Space Western: Society in the future will look like nineteenth-century America, with brave pioneers leaving a civilized homeland to settle a lawless frontier. If aliens are present, they will be a Fantasy Counterpart Culture for Native Americans.

Contrast Schizo-Tech. See also Crystal Spires and Togas. Compare Future Imperfect.

For the sort of thing that appears on the Tales of Future Past website, see Zeerust.

Despite the title of this page, this trope has nothing to do with the 1967 Moody Blues album Days of Future Passed (where the title refers to, well, the present, specifically the course of a single day in a person's life), nor the X-Men Time Travel story arc 'Days of Future Past' (although in the original run of the X-Men story, some of the background details imply a degree of technological regression, such as horses pulling a bus, and that timeline had certainly regressed in terms of social equality into an extreme level of segregation and eugenics).

Anime and Manga

 * Trinity Blood is a Renaissance Future, with Vatican States = Italy, Methuselah Empire = Ottoman Empire, and Albion = England.
 * Code Geass has this, complete with knights in giant robots, an Emperor, princes, and castles. It also has a Feudal Future for the Chinese Federation, which takes up most of Asia.
 * Code Geass is Alternate History - society never advanced beyond a Feudal stage in this timeline, except in parts of Europe and elsewhere, and even then these were constanty outdone by the Brittanians. To be this trope they would have to have abandoned feudalism and imperialism at some point, but most of the world never did.
 * Voltron / GoLion is a medieval fairy tale world In Space.

Film

 * The film adaptation of Dune

Literature

 * The Dune series by Frank Herbet. The neo-medieval nature of the human interstellar Imperium was explained in detail in the novels, but handwaved in the film and TV miniseries. The main historical parallel to the Imperium is the Holy Roman Empire of the European Middle Ages, though elements from various other historical empires, nations and societies are all over the place...
 * Interestingly, democracy or republic never comes up even as an idea. Everybody appears to be ok with feudal rulers and emperors, most of whom don't care about their subjects. Guess Herbert's not a big fan of representative governments.
 * Sort of. It is somewhat understood that the cause for the establishment of the system is due to The Machine War in the distant past.
 * The prequels show that The Empire has existed for millennia prior to the Time of the Titans and the Butlerian Jihad. It was simply reformed after the Battle of Corrin, continuing the old Imperial line. All through the Jihad, the side fighting the machines was called the League of Nobles. Slavery was rampant during the war and after it, flimsily justified by the lack of machines to do the work (why they couldn't just hire workers is not explained) and the fact that the Buddislamics didn't want to join the war against the machines.
 * The Foundation Series: The Galactic Empire is Imperial Rome, the Foundation-era galaxy is Medieval Europe. The entire arc is explicitly modeled on The Decline and Fall of the Roman Empire.
 * The Dragonriders of Pern series by Anne MacCaffrey. Pern was settled in Earth's future, but reverted to a technologically inferior mostly feudal society, partly due to the intent of the colonists, and partly due to the scourge of Thread.
 * Several societies in S.M. Stirling's Emberverse fulfill this trope although it also has a foot in Fantasy Counterpart Culture as supernatural elements creep in during the second trilogy. The Clan MacKenzie is based on a New Age interpretation (much against the liking of its founder) of a Celtic clan, while the Portland Protective Association was deliberately created by an SCA member as a copy of a medieval feudal society with trappings of Mordor. The oddest example are the Dunedain Rangers founded by a mildly insane Tolkien fangirl who has a quasi-religious reverence for his books. There are also several "Indian" tribes many of whose members have, at best, only nominal amounts of First Nations ancestry and Norrheim, a Viking style nation founded by Asatru. Meanwhile over in England "Mad King Charlie" tries to turn what remains of his nation into something of a vast Rennaisance Faire, although his subjects draw the line at Morris dancing.
 * Much of the interior of North America in the Emberverse, and by implication many areas elsewhere, have types of spontaneous neofeudalism; they just don't have the self-conciously archaic vocabulary of the PPA. Instead of "barons" and "knights" they have "sheriffs" and "farmers/Ranchers"; instead of "serfs" or "peasants" they have "refugees" or "evacuees". And they have "emergency governors" or "Presidents pro-tem" (popularly known as "bossmen") instead of Lords Protector or Kings.
 * Cordwainer Smith's books use Chinese Imperial history as a pattern.
 * The novels and short stories of Cordwainer Smith is an interesting subversion, as the humans of the far future are, after living some centuries in a nondistinct, cultureless utopia, actively trying to resurrect the cultures of the past.
 * The Queendom of Sol in ~Wil McCarthy~'s "Collapsium" and its sequels.
 * In L. Neil Smith's Henry Martyn, Bretta Martyn and their Web Comic sequel, Phoebus Krumm the Monopolity of Hanover is based on Tudor England while it's rival, the Jendyne Empery-Cirot is based on Spain of the same period.
 * A Canticle for Leibowitz, which is about a future Earth set in the aftermath of a nuclear war. Society seems to have regressed to the Dark Ages, with only a few brave monks recording the knowledge of humanity for future generations.
 * The Tripods trilogy is a prime example of this. It takes place about 100 years in the future, but society is largely medieval style due to the effect of the Caps on their wearers-curtailing curiosity and causing them to reject technology.

Tabletop Games

 * BattleTech: The Star League is the Roman Empire, while the Successor States are Medieval Europe.
 * Though the return to feudalism is explained in some of Michael A. Stackpole's earliest BattleTech novels. The rise of independent barons and feudal-esque land titles was a pragmatic response to the difficulties of managing the economies and lives of trillions of citizens across hundreds of light-years. Except during the Star League-era, communication and especially travel between star systems is vastly time consuming and expensive (compared to real 21st Century standards), therefore downloading authority for the governing and management of a system to a local governor or baronet is far more expedient than having everything done at a central bureaucracy many light years away.
 * Don't forget, romance sub-plots with royals or young nobility need to happen in a universe tied together by gigantic walking tanks as per Rule of Cool.
 * Warhammer 40'000: Post-Constantine Rome.
 * Fading Suns: Medieval Europe.
 * Traveller: Imperial Rome.
 * Traveller in many ways looks more like The British Empire what with the British noble titles, the nautically derived traditions the exploration and colonization, and the wild frontier regions. Also the relation of the Imperium to it's member worlds seems more British then Roman. Traveller also has a Feudal Future and the nobles have real power.

Video Games

 * Nie R, which takes place 1,400 years after the ending in Drakengard in which Caim and Angelus end up in Shinjuku, takes place in a dying world where humanity is on the brink of extinction and society has since devolved mostly into a pseudo-medieval hellhole, though there are Lost Technology abound.

Western Animation

 * Futurama: The episode The Late Philip J. Fry includes a Feudal Future with giraffes as feudal rulers over humans, along with Futurama relying heavily on the Days of Future Past trope in the whole series. In the pilot episode, while Fry is frozen and there's a montage of progress outside the window, there's a gag where buildings gradually build up and become more futuristic, then flying saucers fly by and destroy everything, then a castle starts to be built (only to be destroyed by flying saucers again).

Anime and Manga

 * Samurai 7 combined the feudal era elements of the Kurosawa movie it was based on with Humongous Mecha. Think peasants farming rice by hand being raided by massive cyborgs aloft with anti-grav.
 * Afro Samurai has a culture of honour combat and sword fighting, in what looks like feudal Japan. With guns, mobile phones and robots thrown in.
 * The manga series Basara takes place in what at first appears to be a fantasy world inspired by feudal Japan. As it's later revealed, it's actually Japan in a post-apocalyptic future.
 * The manga Grenadier reveals over time that this is the case, in an After the End sense, particularly with the appearance of The Dragon's Electronic Eye, and the usage of a solar Wave Motion Gun by the Big Bad as his ultimate weapon during the final battle. The anime adaptation... not so much.

Comics

 * The social order established by Orion Assante in Grendel incorporates a lot of feudal Japanese motifs and elements.
 * Space Usagi anyone?

Film

 * Star Wars, to a degree (the Jedi code of the warrior and Darth Vader having a part-stahlhelm part-samurai helmet).
 * The Jedi robes in general were based on traditional Japanese clothing, to emphasize this.
 * The Force is also loosely based on Daoist teachings.

Literature

 * A planet mentioned in Armor by John Steakley has a feudal society with samurai trappings, deliberately founded by some guy with an enormous pile of money and a big ego. The Emperor is accompanied everywhere by a bodyguard whose duties, apart from the obvious, include beheading anybody who doesn't appear suitably impressed by the Emperor's magnificence. (Fortunately, the current Emperor is genuinely pretty darn impressive.)

Tabletop Games

 * The major exceptions to the above in BattleTech are the Draconis Combine and Capellan Confederation, which are Japan and China, respectively.
 * Warhammer 40'000: Fans often accuse the Tau of being space Japanese, and, thus, anyone who plays them are called Weeaboos. This is perhaps because the costumes and vehicles of the Tau are inspired by East Asian clothing and architecture.

Video Games

 * The Kusari in Freelancer have reverted back to feudal Japan, complete with lords and a shogun, although no samurai battles or ceremonial swords are shown.
 * In , the setting is far future Japan, which has reverted to a feudal system that seems to combine the Yamato and Ainu people's traditions. The rest of the world might be different, but we never see it.

Anime and Manga

 * Cowboy Bebop, as its name implies. The pioneering spirit is somewhat involuntary, being mostly due to the destruction of Earth's moon, scattering all those able to get away across the frontier of the solar system. If there is any "civilized homeland" left, it is on Mars, not Earth.
 * However, this may be due to idiomatic translation. None of the main characters are cowboys in the Western sense. In fact, the DVD extras clarify that "cowboy" in Japanese may be more like "bounty hunter" in English. Which makes sense as ALL of the protagonists are bounty hunters (or want to be). But the Old West themes are still laid on pretty thick.
 * Trigun, much like Firefly, has a Wild West society with advanced technology, but here it's explained as humanity doing what it has to in order to survive on the desert world it's stuck on.
 * Gun X Sword also takes place in a western-style planet with Humongous Mecha. It's more a spaghetti Western than other space-western anime.

Film

 * Star Wars

Literature

 * In Ian McDonald's Desolation Road and Ares Express the non-urban areas of Mars are very much like the Old West.
 * Zack Hughes' For Texas and Zed.
 * Much of the third book of John Birminhaam's Dissapearance trilogy takes place in the western half of the United States whicg has once again become the Wild West only with trucker convoys instead of wagon trains and the cavalry riding Humvees and helicopters. Also no Native Americans since they died along with everyone else. Plenty of Indians from India though as imported workers.

Live Action TV

 * Firefly; there are reasons for the Wild West/Australian Outback aspects of the society, but they are hinted at rather than explained outright.
 * Though it should be known that Chinese culture is also heavily prevalent in this example, with Chinese being a second language to just about everyone.
 * Considering the huge role played by Chinese laborers in the American west (particularly the California Gold Rush country and in building the railroads) it isn't all that surprising.
 * The episode "Heart of Gold" handles it particularly well, with a local ruler forcing everyone to live out his own personal fantasy of ruling an old west town.
 * As with most 19th-century based westerns, a recent civil war between a federal government and break-away "states" frames the story. Incidentally, this makes the crew of the Firefly analogous to former Confederates.
 * Reavers are the embodiment of all of the worst possible stereotypes of Indian "savages", complete with "tribal" drums introducing their appearance on the screen.
 * The original Star Trek the Original Series was described by its creator as being a space western. The show uses western-style fighting and is generally paced and acted as a western.
 * Most of the primary cast had performed in westerns in the past (~DeForest Kelley~ in particular was well-known as a Bad Guy character actor before becoming Dr. McCoy) and westerns were the most popular shows on television during that period, so it's not surprising that Star Trek would follow that pattern.
 * Max Headroom. Lots of retro items still around (or recreated?) {[twenty minutes into the future}}.
 * If one considers the plight of the Colonial fleet as analogous to the Mormon migration to Utah (in keeping with the strong Mormon themes throughout the show), then the original Battlestar Galactica Classic also qualifies.

Tabletop Games

 * Deadlands being a Wild West game, its sequels Hell on Earth and especially Lost Colony have a good deal of the Western about them. While Hell on Earth is set on Earth, but after the advent of space travel, Lost Colony is literally in space, complete with the Native American analog aliens, the Anouk.

Video Games

 * Starcraft : The Terrans are modeled after The Wild West, being pioneers who escaped the oppressive United Earth Directorate, complete with southern drawls and corrupt leaders.
 * Arcturus Mengsk even wears ceremonial uniforms not unlike those from the time of the American Civil War. He's basically clad as a fusion of Robert E. Lee and a Union officer.
 * The Terrans are basically "The Wild West meets (the book version of) Starship Troopers"
 * The Terrans never escaped from the UED. The UED didn't exist then anyway. The United Powers League was going through a "cleansing" period, and anyone who didn't fit their idea of a perfect human (e.g. people with implants, psychics, criminals) was turned into a Human Popsicle and sent on giant ships to another system. Of course, the original idea was to kill them all, so it may count as an escape.
 * Wild Guns. Cowboys and robots!

Western Animation

 * The 80s cartoon Bravestarr.
 * Not to mention Adventures of the Galaxy Rangers.
 * And the trio of 1980s animated Space Westerns wouldn't be complete without Saber Rider and the Star Sheriffs...

Comics

 * Parts of the Cursed Earth in Judge Dredd strongly resemble the Wild West.

Anime and Manga

 * Although Aria takes place on Mars in the distant future, the city of Neo-Venezia was built explicitly as a recreation of classical Venice. Other recreations of Earth include a Japanese temple on a nearby island.
 * Some locales in the different Gundam universes evoke the past 100 years to a certain extent. This is more blatant in Gundam Wing, and even more obvious (though justified) in Turn a Gundam.
 * In a milder example, Martian Successor Nadesico's Show Within a Show, Gekiganger 3, despite being almost identical to the 1970s Super Robot anime it parodies, is said to have premiered in the year 2096.
 * Gungrave, though actually set in the far future on a different planet, captures the 1980s "Greed Is Good" Drug-Lords-of-America-aesthetique rather well.
 * The Galactic Empire in Legend of the Galactic Heroes has a strong 19th century Prussian aesthetic.
 * In Avenger, the civilization on Mars seems an awful lot like the city-states of ancient Greece.
 * Coming back to Cowboy Bebop again, the cities on Mars almost look indistinguishable from current terrestrial ones. They borrow from many examples such as New York and Hong Kong.

Comics

 * Cross Gen's Myth Arc spanned many series and worlds, some futuristic and some seemingly archaic, but all with humans. Meanwhile, back on Earth in Crux, Geromi explains that humanity spread through the universe and colonized a lot of worlds. Which means that every other world we see, from steampunk-Victorian Ruse to medieval-fantasy Sojourn to feudal-Japanese The Path to Roaring-Twenties Mystic (to the ones that actually are sci-fi-ish), is actually in the distant future and was once colonized by spacefaring humans.

Film

 * Dark City, Brazil, and Gattaca all show a particular kind of this trope, focusing on a 20s and 30s Noir look.
 * Star Wars
 * Star Wars counts as all three. The western influence comes in location. Young Luke lives in the middle of a desert on a farm, later meeting up with gunslinger Han Solo in a saloon-style cantina. The designs of the Jedi and Sith are heavily-samurai based, clothes resembling kimono and swords like katana. However, their behavior is medieval-based having a monastic lifestyle and parallels to wizards, especially in Palpatine and Obi-Wan Kenobi. The Jedi Code is a combination of both Bushido and Chivalry, both being similar to each other.
 * The space dogfights were explicitely based on the real thing from WWI, the death star could arguably be compared to things like the impossibly big tank projects Germany had running during both world wars (the K-wagen during the first, the Maus, Ratte and Monster during the second).

Literature

 * Piers Anthony's Cluster series had, as a rule of space colonization, that civilizations would regress in proportion to their distance from the original home planet. It Makes Sense in Context, up to a point, except that they regressed exactly back into the history books; X light years away, you had atomic-age planets; further away than that, you had industrial revolution planets; further away than that, you had medieval planets; all the way out to the edge, where you have caveman planets.
 * Cordwainer Smith, who published in The Sixties, wrote of the Instrumentality of Man and its great project, the Rediscovery of Man. This involved dismantling the sterile utopia that humanity lived in by recreating past societies so that random chance and unhappiness could give people something to live for.
 * In that universe the title planet of his only novel Norstrilia derives its name language and many of its customs from "North Australia" of the 19th and early 20th Centuries.
 * In Charles Stross' Singularity Sky the planet it takes place on is very similar to Tsarist Russia including a smoldering revolutionary movement.
 * Queztalia in James Morrow's Wine of Violence is an idealized take on the Meso-American Toltec civilization.
 * The Space Captain Smith series by Toby Frost is about a hero of the British Space Empire. On the covers he's shown in a red uniform, circa 1880, carrying a rifle that looks like a 19th century weapon with a futuristic scope attached.
 * Neal Stephenson's The Diamond Age takes place on a future earth where people have segregated themselves into several large "phyles," unified not by geography but by shared culture and beliefs. One of these phyles, New Atlantis, has based its laws and cultural practices on those of the American and English Victorian period, with the addition of zeppelins. The underlying idea is that nanotechnology has given everyone the tools to live more or less as they please, and broken the control of territorial governments over their citizens. So people wind up forming factions based on whatever culture they choose to live in. The neo-Victorians just happen to be the ones who adopt the main viewpoint character.
 * Timothy Zahn's Quadrail series is a take on the Golden Age of Railroad, only the railroad is built and maintained by mysterious aliens and stretches between star systems.
 * The urban areas of the Mars of Ian McDonald's Desolation Road and Ares Express have a very Jazz Age feel to them, including the planet's most popular musician being Glenn Miller, who is inexplicably alive in the 28th century and the music of the revolution being swing jazz, salsa and samba.
 * This trope isn't too heavily used in the Honorverse, but several of the societies described have specific historical parallels. The People's Republic of Haven takes on some of the characteristics of revolutionary and Napoleonic France, while the Star Kingdom of Manticore's society and military parallels the United Kingdom during the same era. There's also the emperor of an overwhelmingly ethnic Chinese interstellar polity who nonetheless modeled his empire after Prussia and the German Empire. Before the time period of the novels, Grayson was a moderately-backwards colony akin to feudal Japan, changing to pseudo-Meiji Japan during their first appearance. Other "neobarb" colonies that have lost contact with the outside world and regressed technologically are also shown. And, of course, the space technology of the novels, at least in early books, is set up precisely to allow classic Age of Sail battles in space.
 * The prequel to the "Warlock" series, Escape Velocity by Christopher Stasheff uses three, on different planets:
 * Wolmar echoes the American Old West of fiction, with forts and traveling peddlers and an on-going war between the settlers and the natives.
 * Otranto is a destination-vacation planet based on Victorian "Gothic" fiction, both romance and horror. Lampshaded in that The Castle of Otranto was a major work in the genre.
 * Gramarye is a planet originally settled by members of the Society For Creative Anachronism; it was deliberately set up to follow the structure of medieval Europe.
 * All The Things I've Done by Gabrielle Zevin takes place in Manhattan in the late 21st century, but has more elements of The Roaring Twenties only without the "roaring" part. However, instead of alcohol being prohibited, it's chocolate and coffee that are prohibited(the main character's family runs a chocolate factory). In fact several offhand comments made by older characters suggest that the world is, in fact, stagnant.

Live Action TV

 * The Enterprise visited a few worlds that paralleled Earth's history. Strangely, each time they found a different explanation for that world's existence. In "Bread and Circuses" they encountered a world that mirrored a 20th Century Roman Empire with Christianity beginning to emerge (Kirk mentioned a theory of "parallel evolution"). "A Piece of The Action" had a planet re-enacting The Roaring Twenties (previous Federation visitors left a book about Chicago mobs behind, and the locals made that their bible). "Patterns of Force" had a world modeled after Nazi Germany (a historian tried to restore the world's collapsing society, hoping to avoid the evils of the Nazis, which went about as well as can be expected).

Web Comics

 * String Theory takes place in the United States, where it's scientifically the 2050s but morally/socially the 1950s.
 * Beckey (creator): Unfortunately, in the world this comic’s set in (the 1950′s of the future!), people aren’t very accepting or understanding of different sexual orientations. Actually, folks aren’t very accepting in general. It’s a distrust of foreign cultures and ideas, mostly, mixed with good old fashioned repressed victorian standards and ideals.
 * Zombie Ranch shows a world where, in the wake of a Zombie Apocalypse, the reaches of the Southwestern U.S. seem to have reverted to an Old West/frontier model of society. Even the Safe Zones seem to have adopted variations on old-time fashion and accessories alongside more modern ones.

Western Animation

 * The Superfriends has several episodes set on alien planets based on periods of Earth history. Texacana is a wild west planet, Camelon is a medieval planet, and Zagdad is an Arabian Nights planet.

Video Games

 * It can be assumed that the pre-Armaggedon American society was something like this in the Fallout series of games. While much of the technology was pretty advanced by today's standards (laser guns and robots), the computer monitors were all monochrome CRTs and everything had a very retro 1950's feel to it.
 * Could be described as "Vacuumpunk", with most technology being based (or at least having the appearance of being based) on vacuum tube technology.
 * Caesar's Legion (pronounced Kai-sar by the legionnaires) is a huge slaver nation with the style of dress based on military uniforms of Ancient Rome. The ranks are also borrowed from Rome: legionnaires and centurions. Of course, by that token Caesar himself should be wearing the imperial purple.
 * Mother 3 takes place in a future in which society has been taken back (or forward?) because  They are fascinated when machines are brought to them via time travel, and they start off not using money.
 * The setting of the Iron Grip games is a mostly feudal Steampunk Low Fantasy world, but it's generally hard to pigeon-hole one or even two single historical eras it resembles the most. In broad terms, it has a blend of culture, architecture, tech and overall atmosphere that wouldn't look out of place in eras as varied as The Middle Ages, The Renaissance, the Thirty Years War, the Napoleonic Wars, Victorian Britain, Tsarist Russia, World War One, World War Two, the decades between them... Not only Culture Chop Suey, but full-blown Era Chop Suey as well...

Real Life

 * Truth in Television: Many social reformers have deliberately attempted to re-create the past (as they saw it). Notable examples include the Holy Roman Empire (an attempt to restore the Roman Empire - "Kaiser" and "Czar"/"Tsar" are all derivatives of "Caesar"), Imperial Japan after Perry's arrival (an attempt to recreate the older Imperial Japan), and the Amish (an ongoing attempt to recreate the "simple" world that existed before the decadent, technological 16th century).
 * With the Amish, it's a little more complicated than that. They shun advanced technology because they feel it detracts from the simple world, but they're not specifically trying to mirror any specific time in the past. So while they don't want a phone in their house, they don't mind using modern chemical fertilizers on their fields. It's more of a conscious attempt to create an Arcadia by excluding elements -- technological and other -- which would detract from their image of the ideal community.
 * It's also not unusual for an Amish town to keep, for example, one phone to call for help in an emergency.
 * And then there's the Society for Creative Anachronism.
 * The founders of the United States drew very heavily on ancient Rome as a model when writing the Constitution.
 * Well, yes and no. The original Articles of Confederation were more-or-less openly based on the constitution of the Republic of the Seven United Netherlands (aka the Dutch Republic of the Seven United Provinces and--most tellingly--the United Provinces of the Netherlands). However, this didn't really work: the Netherlands is small and was dominated by a single member state--Holland, and particularly the city of Amsterdam--whereas the United States is large and no one state dominated the others. The 1787 Constitution was not-so-secretly modeled on the British constitution as it stood at the time (as soon as the Framers had the brainstorm that the states serve the same role in a federation as the Lords did in Britain, things just kind of fell into place). However, there was a definite Roman influence in everything from the names of institutions (most conspicuously the Senate) and certain institutional arrangements: the presidential vs. the tribunal veto (although that one is also similar to British Royal Assent) and the elaborate system of checks and balances (as opposed to the British system, which any clear-eyed observer recognized basically made Parliament a collective absolute monarch) are the clearest examples.
 * I think more direct influences were Montesquieu's mis-understanding of the British system, though come to think of it you'd think English colonists would know better; and the different interests of the small and big states. Senate and House are more of a rationalized compromise than a principled design.
 * The architecture of Washington, D.C., however, is definitely evocative of ancient Rome.
 * Notably the "Freudian obsession with big marble pillars"
 * With the Washington Monument being Egyptian for good measure.
 * At any rate, Nazi Germany and fascist Italy did try and emulate Rome (Imperial rather than Republican), in a fashion.
 * And the 3rd Reich also emulated certain elements of Sparta, from murdering children who were born with defects to the propaganda catchphrase "Only German women give birth to real men." (a paraphrase of an actual quote from Queen Gorgo).