A tower taller and wider than the Shard was once planned to stand in the heart of the City of London. Penned by Sir Norman Foster, the Millennium Tower would have stood more than 380 metres high and looked down on The Shard across the river.
In the early days of the motorcar, architects were already looking to what would replace it as the popular transport of the upper classes, and obviously, private helicopters were to be the transport of choice.
In 1938, as ideas were being made for the defence of London, plans were shown off to surround London with a massive "aerial mine-field" made from over a thousand deadly balloons.
Compared to the great monuments of ancient lands, there are few if any buildings in London which can withstand the ravages of the millennia, and it's time to build a mighty monument so that future generations can remember the grandeur that is the capital of a mighty empire.
Trafalgar Square's a big empty space isn't it. Surrounded by roads full of cars looking for somewhere to park. What a waste of space it is. Lets turn it into a car park!
There were once plans to build a cable car that would link the Millennium Dome with the DLR on the north side of the river. Obviously, no such cable car was ever built.
In the early 1890s, a Scottish architect published a grand scheme to rebuild central London. Away with tired old narrow streets and hello to Parisian boulevards. Goodbye to St James' Park and hello to a massive road network and roundabout.
Today, the land behind Paddington station is an array of glossy office blocks. But they shouldn't be there. It's supposed to be a 1960s array of housing towers.
No not that one, the other one. No, not that one either, the other one. Yes, this one -- the giant airport right in the centre of London on the Thames, next to Parliament.
In an age where people were thinking the future of mankind was more leisure and less work, thoughts turned to how such pleasure was to be enjoyed.
A massive pyramid, topped with a pillar, and then some more -- not the Post Office Tower, but a monument to the Battle of Britain.
The River Thames is a rather curvy beast, especially around the Isle of Dogs, but had a plan in 1796 been carried out, it would be considerably straighter.
Greenwich could today be less famous for its observatory and meridian, than for a gigantic statue which would have dominated the area.
In 1967, the Conservative Party published a document calling for the scrapping of buses in central London - and replacing them with a huge Monorail network.
In 1832, Parliament passed the Great Reform Act, and London's skyline was nearly as radically reformed, with a 1,000 feet tall gold plated column to commemorate the occasion.