Because that is where it is.
It started as a very small settlement in pre-Roman times.
To defend London, was built by William the Conqueror It was built as his home in London.
London is built on clay, not on a rock.
In london
The cenotaph was built in Whitehall, in London after WWI.
The London Wall was first built by the Romans.
london was built upon clay and not rock
London
London
It was there already. London was built around the river.
it was built in London, England over the Thames river
To defend London
James Burbage built the first theatre in london in 1576