The 'square' is hard to make out now, reduced to a pair of detached stubs by the construction of Clerkenwell Road in 1878. But from the 12th to the 16th century this was the heart of the inner precinct of St John's Priory, the English headquarters of the Knights Hospitaller.
Address: St John's Square, London EC1V 4JJ
Latitude,Longitude: 51.522827, -0.103296