St Mary at the Walls church dates from the 15th century. It was extensively damaged during the Siege of Colchester in 1648. The reason for this is that Thompson, a one eyed gunner, had placed himself and his cannon on top of the tower and was causing considerable damage to Lord Fairfax's attacking forces. This brought a concentration of Roundhead fire onto the church. Eventually, Thompson and his gun, came tumbling down. The damage can clearly be seen as the tower was repaired around 1750 in brick, instead of the re-used Roman materials with which the rest of the tower is constructed. This church was also the site at which Protestants were burnt during the reign of Mary I. The largest number of 'heretics' was burnt in Colchester in Britain after London. The body of the church is Victorian with the repaired Norman tower.