This large church dates from the mid-12th century. There may have been an earlier church, but the new church was built on a cruciform plan the earliest part being the chancel. The chancel was quite long for the mid 12th century. The church consists of chancel, crossing tower, north and south aisles, nave, transepts and north and south Chapels. The late 12th century nave has five bay arcades with round piers, the second piers from the west are octagonal. The church was one of the largest in Sussex in 1200, and a north Chapel (Clare Chapel) was added in the early 13th century. Later in the 13th century a south Chapel was added. In the 14th century both aisles were heightened and battlemented. In 1377 and 1448, the city was burned down by the French. This seriously affected the town's prosperity and there are signs of fire damage in the crossing which suggest it may have even collapsed. The rebuilding was uncoordinated and lengthy and there are three different types of crossing arches. There is a low, battlemented tower with a squat spire is said to have been renewed in 1702. There is a fine view from the top. There are 8 bells - which were once stolen by the French. They were recovered on a return raid by local men. Flying buttresses were added to the south east side of the church which suggest structural instability, possibly after the raid. By the early 18th century substantial repairs were necessary to the church, further repairs followed in the 19th century. The church features a clock dating from around 1560, with a long 18 foot pendulum which swings in the church. This is one of the oldest working church tower clocks in the country. On the north face of the tower are two gilded quarter boys with bells. These are fibreglass replacements of the originals which are now kept in the church. The font dates from 1845 and is a copy of the one at Newenden church in Kent. In 1790 a west gallery was installed, entailing the blocking of the west doorway. It remains blocked.