St Michael at the North Gate
The Saxon tower of St Michael at the North Gate is most likely Oxford's oldest building, rivalled perhaps by the tower of St George which is part of the castle complex. Whilst the church that was originally attached to the tower was built sometime between 1000 and 1050, the tower is thought to have been built about 1040. It's presence here on the Cumbrian Castle Listing, is owed to the fact that the tower and church originally formed part of Oxford's walls, and the North Gate (hence its full name) and also owing to recent research on Saxon church towers and their high status use as personal chapels and dwellings all housed within a tower of sufficiently thick walls as to offer an element of defence.
Above. The Saxon tower of St Michael.
Above. Sketch based on archaeological evidence.
The sketch shown above, shows the nave to the South of the tower and situated on Ship Street, with the tower forming part of the gateway into Oxford. The Saxon city wall (built to protect the ancient Saxon Burgh) ran to the North of the church. As far as I'm aware this is a unique arrangement where the presence of a sturdy church tower has been incorporated into the city's defensive ring of walls and ditches. It has been suggested that there may have been another tower to its West, though no archaeological evidence has yet been found of this additional building.