We asked Rowan Moore to pick his top five architectural follies, and here they are - an eclectic mix from around the world and across the centuries.
The Millennium Dome, London
The Millennium Dome, designed by architect Richard Rogers, opened to the public on 1st January 2000 and closed on 31st December the same year. The twelve yellow support towers represent the twelve hours of a clock's face, or the twelve months of the year.
Fonthill Abbey, Wiltshire
Commissioned by William Thomas Beckford in 1796, the Abbey was designed by architect James Wyatt. The tower, which stands at 90m, collapsed twice before it was finally built in stone. It collapsed again in 1825, but by this time Beckford had sold it.
The Olympic Stadium, Montréal
French architect Roger Taillibert designed this for the 1976 Olympic Games in Montréal. There is a lift inside the tower to three viewing platforms. It's taller (the tallest of its kind, in fact,) than the other, more famous leaning tower.
Ceauşescu’s Bucharest Palace of the Parliament, Romania
Construction of the 1,100 roomed 'People's Palace' began in 1983. In order to make space for the building, 19 Orthodox Christian churches, 6 synagogues and Jewish temples, 3 Protestant churches (plus eight relocated churches), and 30,000 homes in two neighbourhoods were demolished.
1 million cubic metres of Transylvanian marble were used in its construction, and, 3,500 metric tonnes of crystal make up the 480 chandeliers, 1,409 lights and mirrors that were manufactured.
It is rumoured that 20,000 labourers worked in 24-hour shifts, seven days a week to complete the palace - though by the time of the People's Revolution in December 1989 the finishing touches were still being added.
Deans Gardens, Atlanta
This 32,000 square foot 'mega mansion' was completed in 1992. Two years later, owner Larry Dean, who made his fortune in software, wanted to sell. It promptly sat on the market for seventeen years, until entertainment mogul Tyler Perry bought it in 2010 for $7.6 m dollars. The original asking price was $40 m. It has fifteen bedrooms (most themed by country or region), an eighteen hole golf course, and a Hawaiian art gallery. It is rumoured that Tyler Perry plans to rase the house to the ground and build something more environmentally friendly in its place.
Tell us what you think is the world's biggest architectural folly in the comments below.