Pneumatic Elevated Railway – 1880 – Rufus Henry Gilbert

Henry Gilbert’s design was a hybrid of Alfred Beach’s air-powered underground and Charles T Harvey’s cable-powered elevated railway. Passengers would be moved through a double row of ‘atmospheric tubes’ suspended from wrought-iron Gothic arches, held on slender Corinthian columns. The Wall Street Panic of 1873 killed Gilbert’s untested scheme but a conventional steam-powered elevated railway was eventually built – the Sixth Avenue El opened in 1878. It closed in 1938 and was razed the following year. All images courtesy of Metropolis Books

North River Bridge – 1887 – Gustav Lindenthal

Gustav Lindenthal – designer of the Hell Gate and Queensboro bridges – once proposed a 6,500-ft long bridge strung between two steel towers soaring 500 feet above the Hudson river. On either shore, 17-storey anchorages dwarfed the buildings on the Hoboken and 23rd Street landings, each containing 50% more masonry than the largest Egyptian pyramid. Ground was broken and a foundation laid in Hoboken, but the crash of 1893 scuttled the privately funded enterprise

Grand Central Terminal – 1903 – McKim, Mead and White

Grand Central Terminal’s magnificent Great Hall almost never existed. McKim, Mead and White – renowned for Penn Station and other grand Beaux-Arts edifices – were favourites to win a 1903 competition to design the station. They proposed a 14-storey building highlighted by a 60-storey tower resembling a Catalan church campanile. Park Avenue, elevated above the exposed tracks outside the station, was to run straight through the terminal. Inside, the barrel-vaulted hall recalled the great railway sheds of Europe. A rival scheme won the day

National American Indian memorial – 1909 – Thomas Hastings and Daniel Chester French

The memorial was the brainchild of Rodman Wanamaker, son of a men’s clothing-store king, who came up with the idea one night after dining out with Old West showman Buffalo Bill Cody. The plan included a statue Indian chief, his hand extending to sea in the sign of peace. It won congressional approval and President William Howard Taft broke ground in 1913, but the first world war and waning interest from Wanamaker meant the memorial was forgotten

City of New Manhattan – 1911 – T Kennard Thomson

From Ellis Island to Battery Park City, New York has been built on landfill, but few plans were as ambitious as T Kennard Thomson’s proposal to create 50 square miles of land and 100 miles of new waterfront in Upper New York Bay. Despite much attention and flashy endorsements, the $600-750m plan never received municipal backing

Skyscraper bridges – 1925 – Raymond Hood

Raymond Hood – designer of 30 Rockefeller Plaza, the Daily News Building and the American Radiator Building – planned a series of ‘apartment bridges’ to reduce congestion and provide a unique, water-focused lifestyle. The plan featured 50 to 60-storey towers of apartments for 50,000 people on either side of a broad roadway built on a suspension bridge. There were shops, theatres and walkways, while lifts granted residents access to the river. ‘Not to embrace this opportunity is to neglect the very pick of metropolitan locations,’ said Hood

Convocation Tower – 1929 – Bertram Goodhue

As skyscrapers proliferated across New York, architects imagined new forms for the tallest buildings. One of the finest was sketched by Bertram Goodhue, who had designed a number of churches in the city. Goodhue came up with Convocation Tower, an 80-storey, 1,000-ft-tall, streamline Gothic skyscraper cathedral for the Interchurch World Movement on Madison Square Garden. Its main floor would have contained a church, with commercial tenants above, helping the congregation pay for its operations

Manhattan airport – 1945 – William Zeckendorf

Even for real estate mogul William Zeckendorf, the plan for a 144-square-block airport rising 200 feet above street level was over the top. He hoped the city would finance the $3bn cost of the airport, which would stretch from 24th to 71st streets, and from Ninth Avenue to the river. Factories, shops, apartments, railways and steamship terminals would all be built beneath the vast deck. Life magazine featured the plans in 1946 under the heading ‘New York City’s Dream Airport’, but commissioner Robert Moses dismissed the plans as ‘ridiculous’.

Hyperboloid – 1954 – IM Pei

As railways struggled nationwide in the 1950s, redevelopment proposals were sought for Grand Central Station. New York Central Railroad chairman Robert Young argued that not utilising the air rights above the building was like sitting on farm land worth $100m and never farming it. Young and William Zeckendorf brought in architect IM Pei to design the Hyperboloid, a 108-storey hourglass office tower which would have been the world’s tallest, with a transit hub at its base. Young’s suicide in 1957 halted any hope for the building

Dodger Dome – 1955 – Norman Bel Geddes and R Buckminster Fuller

A few years before the Brooklyn Dodgers moved to Los Angeles, owner Walter O’Malley tried to replace Ebbets Field with a domed stadium on Atlantic Yards, site of the Barclays Center arena today. O’Malley consulted designer Norman Bel Geddes, who imagined a fixed dome with retractable roof, floored with a precursor of AstroTurf. Buckminster Fuller – of geodesic dome fame – developed plans for a translucent fibreglass structure to seat 55,000. A scheme was hatched to float $30m of bonds, but the Dodgers eventually moved to LA

Metropolitan Opera House – 1955 – Wallace K Harrison

Harrison’s first ideas for the Met were fantastical. One of his earliest sketches looked similar to the Sydney Opera House; another presented a wavelike building on stilts above a reflecting pool. His most absurd version was surely the Met as a gigantic Roman foot, its base resembling a narrow stone ankle, spreading apart until its toes formed the looping curtain walls that today mark the front of the structure. But after almost 50 proposals, project patron John D Rockefeller and the board finally accepted the least visionary of them all

Ellis Island ‘city of the future’ – 1959 – Frank Lloyd Wright

After the immigration centre was decommissioned in 1954 the site was offered to developers. The highest bid proposed a ‘completely self-contained city of the future’ designed by recently deceased Frank Lloyd Wright. It featured a circular podium superimposed on the rectangular island. There were thousands of apartments and a 500-room hotel. Air-conditioned domes would house theatres, hospitals, churches and schools. Cars would be replaced by moving pavements. All proposals were rejected and the island was declared a national monument