London's extreme measurmements?

Question

I would like to know the diameter of London at it's widest point(s)

I would also like to know what the highest point within London is.

I need the info for a piece of fiction i'm writing.

Answer 1

London is practically exactly 30 miles across at its widest point

Its highest point (built) is the roof of the One Canada Square tower, commonly known as the Canary Wharf Tower, its 235m

The highest natural viewpoint in London is Westerham Heights, Bromley, at 804 feet (245 m)

However, this is quite far out. The highest natural viewpoint in central London is Hampstead Heath (the North End) at 134m