O Oranges and Lemons - Say the bells of St. Clements...
The Great Fire of London destroyed several of the churches mentioned in the rhyme, and most still there now are not the original buildings/exact locations.. St Clements is in East London , near to the Thames and has been rebuilt several times. It was close to a wharf where citrus fruit used to be unloaded, hence the lyrics.
I have been in the crypt in St. Martins , off Trafalgar Square, which is normally open for coffee, snacks, etc.. Quite nice down there! Think that the church is a rebuild of the one in the rhyme . The original was close to a site where money-lending/currency exchange took place, hence the lyrics.
"Oranges and lemons" is a very old rhyme, and the churches mentioned were mainly in the old City of London, an area on the north bank of the Thames, a mile or two east of the modern city centre of Trafalgar Square, Oxford Steet, Houses of Parliament, etc. The Tower of London is also out there , which is the reason for the gruesome finish to the rhyme!