On the banks of the River Thames at Greenwich from 1443 to 1660 sat a spectacular palace. It was the Palace of Placentia.
This is a good quiz question and the answer is under the Museum of London! Underneath the museum of London (which is built on a roundabout) in the bunker-like bowels is a collection of a completely different kind that is not open to the public.
In the spring of 2010, archaeologists found six timber piles on the foreshore at Nine Elms which would have been part of a bridge to an island in the River Thames.
Two men who put the stone circle at Avebury on the map never met, but both had a passionate interest in the stone circle.