The surviving ruins of the priory church, of flint rubble with dressings of Roman brick and some Barnack and limestone, date mainly from the early to mid 12th century, and seem to be of the church consecrated in 1177. They consist of the remains of seven bays of the aisled nave, and of the elaborate west front flanked by towers. Excavation has revealed a small north transept, a south transept with a crypt or undercroft beneath it, and a short, square-ended, chancel. The crypt extended under the crossing, and presumably also under at least part of the chancel. The nave had a high triforium above the squat, circular piers of its arcade. The central west doorway retains much of its stonework and is described below, along with the scant remains of the N doorway of the W facade. Above the doorways are two tiers of intersecting wall arcade, all of brick with no sculpture, and above them was a rose window flanked by two round-headed windows. Of these the rose is largely gone along with the window on its N side, but parts of the stonework of the window to the S of thye rose remains and is recorded below. Above them is the remains of a brick stringcourse, and above that again was another brick wall arcade. In the 14th century new windows were inserted into all but the easternmost bay of the north aisle. The church survived the suppression of the Priory in 1536 as it had been the parish church of St Botolph's for some time. It was ruined in the siege of Colchester in 1648, and further damaged in an earthquake in 1884. The ruins were repaired in 1887-88 and again, by the Ministry of Works, in from 1912. The west front was cleaned and repaired in 1990-91.