London gets a round of its own in a great many British quizzes, and the questions are more specific than general geography: they are about the Underground, the bridges, the boroughs, and the buildings whose real names differ from the ones everybody uses.
The Underground
Tube questions are the reliable core, and they are almost all about the network rather than the journeys: which line is which colour, how many stations, which station has the most platforms, which is the deepest, which are the only stations containing all five vowels or none of the letters in "mackerel". Setters love these because the answer is checkable and the reasoning is impossible.
The Circle line is no longer a circle, several stations have been renamed, and a number of disused stations still exist — all three are standard questions.
Buildings, bridges and boroughs
Big Ben is the bell, not the tower, and the tower's name has changed within the last fifteen years: this is probably the most-asked London question there is. Tower Bridge and London Bridge are routinely confused on purpose, and the sale of the old London Bridge to an American buyer is asked about constantly.
Beyond that: the number of boroughs, which are royal, what the City of London is as distinct from London, the Monument and what it commemorates, and the livery companies. The Great Fire and the building of the sewers supply the historical questions; the Thames Tunnel and the Channel Tunnel the engineering ones.