The Priory of St John, established in 1099 in England, occupied a large area of Clerkenwell, in London. The Priory suffered the fate of many religious places under Henry VIII, and all that remains of the original structures is the gateway rebuilt by Sir Thomas Docwra in 1504 after rioters had destroyed the previous gateway.
Site plan and photo of the lost East Window, from "The Order of the Hospital of St John of Jerusalem and its Grand Priory of England" by H.W. Fincham, 1915
Photo of the Gateway interior of St John's Church is courtesy of Jo Christopher nee Docwra.
Photos of the heraldry from the DFRP collection.