Throughout history there have been many fantastical and outlandish urban projects that never made it past the drawing board. From Hitler's dream of a new Berlin to a sealed dome over Manhattan, here are some of the most incredible.

Following the Great Fire of London in 1666, genius architect Christopher Wren conceived a grand symmetrical redevelopment plan for the city, most of which had been razed to the ground. Inspired by the splendid boulevards and buildings of Paris, the plan features wide avenues, spacious piazzas and classical edifices.

Wren's grid-based plan wasn't meant to be. Overly ambitious and prohibitively expensive, the project was eventually abandoned and property owners ended up rebuilding on their existing plots. This illustration commissioned by New London Architecture shows what the city would have looked like if the plan had gone ahead.

The environs of Paris might have resembled Manhattan if this grandiose project had been given the green light. Reinforced concrete pioneer Auguste Perret envisaged Les Maisons Tours (The Tower Houses) in 1922, a succession of 300 residential Empire State-like skyscrapers on the city's major ring road.

Connected by sky bridges, the towers would have topped out at 985 feet apiece, which is in the same height bracket as The Shard in London and New York's Chrysler building. Needless to say, the sheer scale and massive cost of the project ensured it never saw the light of day.

In 1960, trailblazing engineer Buckminster Fuller dreamt up a "geodesic dome spanning Midtown Manhattan that would regulate weather and reduce air pollution." Covering two miles of the island, the mile-high dome would have warmed the city in winter, cooled it in summer and cleaned the air all year round.

Fuller believed the dome would pay for itself in under 10 years with the cash saved from snow removal in winter and he was convinced the city authorities would opt for the project one day. Ultimately, the dome was never taken seriously. In any case, the structure would no doubt have been far more expensive than Fuller anticipated.

Staying in the Big Apple, New York City would have given Barcelona a run for its money in the architecture stakes if Antoni Gaudí's skyscraper plan had been realized. Commissioned in 1908, the eye-catching tower, which would have stood 1,180 feet tall, was earmarked to house a cultural center, restaurants and hundreds of apartments.

News of the project only surfaced in 1956 and exactly why Hotel Attraction was never built is unclear, but in 2003 the building was put forward as a replacement for the World Trade Center. Hotel Attraction was featured in Fox's alternate universe show Fringe (pictured), which gives you an idea how the skyscraper might have looked in the city.

A rooftop airport in Midtown Manhattan – what could possibly go wrong? This bizarre plan was the brainchild of real estate developer William Zeckendorf and featured in the March 18 1946 issue of Time magazine.

Sprawling over 990 acres, the airport would have covered 144 blocks and was to have featured ship docking areas. As might have been expected, the projected $3 billion (£2.4bn) price tag ($37 billion/£29.7bn in today's money), not to mention the massive disruption it would have caused, scuppered Zeckendorf's dream.

In 1932, Modernist architect André Lurcat came up with this idea for a relay airport for light aircraft called Aéroparis, which would have been located on an artificial island in the middle of the River Seine, not far from the Eiffel Tower.

While Lurcat's idea was purely theoretical and wasn't looked upon as a viable project by the powers that be, a similar proposal was adopted in the UK capital: London City Airport is basically a repurposed quay surrounded by water.

London City Airport is all well and good, but London may have had its very own city center airport situated on a platform over the River Thames at Westminster if this wacky idea had come to fruition. This illustration appeared in Popular Science magazine back in 1934.

In fact, London seems to have a thing for river airports. Since the 1940s, several serious projects have been considered and rejected by the planners from the Thames Hub Airport to London Britannia Airport, nicknamed 'Boris Island' after then-Mayor of London Boris Johnson (pictured).

In 1933, Neoclassical architect Boris Iofan won a competition to build Moscow's Palace of the Soviets, a gigantic structure topped with a huge statue of Lenin. The edifice was to be built on the site of Christ the Savior Cathedral, which was bulldozed in 1931 in preparation for its construction.

The Palace of the Soviets would have been 1,624 feet tall, making it the tallest structure in the world at the time, and was to have housed the Soviet legislature. Construction began in 1937 but stopped during World War II and was later abandoned, and the cathedral was painstakingly rebuilt in the late 1990s.

This horrifying illustration appeared in a 1938 issue of the Illustrated London News. Thankfully, it was never even considered. The drawing was commissioned to lampoon the 1937 Bressey Report, which advocated redesigning London as a car-focused city.

Although the multi-story car park idea was never considered, this equally bizarre 300-foot pyramid on Trafalgar Square made it all the way to a public exhibition in 1815, but the $1.2 million (£1m) cost ($102 million/£82m in today's money) proved prohibitive.

Soaring into the Chicago sky, the mile-high Illinois skyscraper was designed by renowned architect Frank Lloyd Wright in 1957. The 528-story tower, which was slated to be made in steel, would have hogged the Windy City skyline, and then some.

Unfeasible, impractical and outrageously expensive, Lloyd Wright's supertall skyscraper was never built but its influence lives on in the current tallest building in the world, Dubai's Burj Khalifa, which was partly inspired by The Illinois.

With its imposing Brutalist towers, this may be many people's idea of architectural hell. But Ville Radieuse (Radiant City), as it was christened, was game-changing architect Le Corbusier's vision of a perfect city. The Franco-Swiss visionary conceived the project in 1924.

Like the Illinois, Radiant City didn't make it past the drawing board, but it more or less lives on too. Brasilia, Brazil's 'new' capital that was founded in 1960, is based on Le Corbusier's Radiant City and incorporates many of its design principles, as do numerous social housing projects worldwide.

London's Covent Garden is one of the city's major tourist attractions with an attractive array of 17th-, 18th- and 19th-century buildings. But all this was threatened with demolition in 1968. A harsh Brutalist scheme was floated by the Greater London Council, which would have covered most of the area with concrete structures.

Luckily, the ghastly revamp was eventually ditched following a campaign by local residents and the area was sympathetically repurposed as a shopping, dining and entertainment destination, retaining its period character. This image, which featured in a 2013 English Heritage exhibition, shows what the area might have looked like if the plan had been successful.

The Almost Lost: London’s Buildings Loved and Loathed exhibition also highlighted this proposed redevelopment of the neighboring Soho district. This 1954 plan by architects Geoffrey Jellico, Ove Arup and Edward Mills, would have wiped out the area and replaced its Georgian and Victorian buildings with five monstrous tower blocks built on a raised concrete platform.

The development would have also featured glass-bottomed canals, landscaped gardens and tennis courts. Fortunately, the hugely damaging scheme was rejected by the local council, and Soho was preserved. Many of London's landmarks weren't quite so lucky. For instance, the Victorian era Euston station and its triumphant arch (pictured) were unceremoniously destroyed in 1962 to make way for a soulless redevelopment.

In an attempt to help solve New York's housing shortage, architect Raymond Hood, who went on to design the Rockefeller Center, came up with this jaw-dropping plan in the 1920s for a series of bridges over the Hudson housing numerous 60-story towers.

Like most of the projects we've looked at, Hood's skyscraper bridges plan was deemed impractical and completely unaffordable, but his design for the Rockefeller Centre managed to work in some of the plan's Art Deco motifs.

If the Nazis had won the war, Berlin would have looked like this. Designed by Albert Speer, 'the first architect of the Third Reich', Welthauptstadt Germania (World Capital Germania) was Hitler's redevelopment plan for Berlin and would have involved destroying 100,000 homes and famous landmarks such as the Brandenburg Gate.

A totalitarian nightmare, the city would have been dominated by a colossal Great Hall and reorganized around a monumental 'Avenue of Splendors'. This image from the video game Wolfenstein: The New Order shows what it might have looked like in 1960.