The foundations of a 13th century masonry-built chapel survive next to the entrance of Colchester Castle, with evidence of four phases.

A Norman chapel was preceded by at least two late Anglo-Saxon structures. The latest of these (dated to c.AD 1000) was interpreted as a single-celled apsidal building built of masonry, which pre-dated the construction of the Castle keep, but which was retained. A timber-frame structure with walls of plaster and infill over wattles. Excavation revealed patterned late Saxon wall plaster.<4> The alignment of the chapel also suggests a pre-conquest date as it situated at an angle to the castle, making it defensively awkward.

The foundations of the 13th century structure was cleared in 1932-1933 and are still exposed. The chapel consisted of a rectangular building c.6.8m wide x c.14.9m long, with a simple apse at the east end structurally undivided from the main space. The east end was subsequently squared off by the insertion of a wall between the north and south walls. All the walls are built largely of septaria, with some Kentish rag and Roman tile fragments.<1>

A number of burials (MCC9291) have been found near the entrance to the Castle, lying over the ruins of the chapel, barbican and forebuilding, themselves sealed by demolition rubble of 1683.<5> Drury suggests they relate to the use of the keep as a prison during the late 16 and 17th century (until 1633).

Between 1931 and 1934 a series of excavations were undertaken to the south of the Castle Keep by Dr. P.G. Laver, assisted by E.J. Rudsdale. Immediately to the south of the keep excavations in 1933-4 revealed two medieval fore buildings, a barbican, a chapel.<3>

In October 1977 a trench was opened (by P. Drury) between the Castle Keep and the Bailey Chapel. The trench was c.2m wide and located immediately to the east of the barbican wall. The investigation was intended to clarify the stratigraphy in the area and in the hope of obtaining a stratigraphic link between the keep and the chapel. The latter aim was defeated by the presence of massive post-medieval disturbance, all levels having been truncated by the 1933-4 clearance of the chapel foundations. Excavation below these levels was limited to a pit and hole which had exposed the surviving section of the facing wall. A shaft was also sunk into a massive robber pit.<3>