Geograph - photograph every grid square

The low walls below the second arch of the railway viaduct from the west, between the Black Gate and the Castle Keep, are the lower courses of a square structure 6.25m across, thought to be the tower of a late Anglo-Saxon Church. First discovered during 19th century railway construction, archaeological excavations between 1977 and 1992 revealed around 600 burials in what was the cemetery of the church. It is possible that the church wasn't demolished but incorporated within the walls of the Castle when it was built.