Along with Northumberland, Kent is one of the two cradles of early English Christianity. Northumberland was the land of saints such as Aidan, Cuthbert and Wilfrid, home to Bede and Benedict Biscop. It was the crucible where Celtic Christianity from Ireland met the Roman Creed, culminating with the “victory” of the latter at the Synod of Whitby in AD664. Kent, on the other hand, saw the arrival of St Augustine in AD597, the establishment of the Roman way and the establishment of the Archbishop of Canterbury. Like Northumberland, Kent still has a slew of churches founded in that seminal seventh century, of which Minster in Thanet is one.
The clue is in the name of course when we say this was a monastic church. It was probably built of wood, mud and thatch and was used by nuns until its destruction by the Vikings in AD1011. The church was given to Canterbury Cathedral in AD1030 so there was obviously a late Anglo-Saxon era replacement for the destroyed church. Simon Jenkins claims that the west wall is Anglo-Saxon but I have not seen any support for that assertion.
The two western bays of the nave are believed to pre-date the other Norman parts of the church. There is, however, speculation that the arcade walls of the three western bays were part of the earlier Anglo-Saxon church - although there is no evidence other than that the walls here are thinner than at the western end. Two blocked Norman windows on the arcade walls indicate that there were no aisles at that time.
From AD1150 the church was considerably extended. Both walls were pierced to allow aisles to be built. The additional bays on the south side are stylistically earlier than those on the north so the south aisle was probably added first. The western tower was added later in the twelfth century with three stages with a turret stair. The west door, sadly, is neo-Norman!
In the early thirteenth century the entire east end was remodelled. A chancel of four bays was added in the Early English style. Transepts were added on each side, again in the EE style. The chancel had stone quadripartite vaults, but there were only added to the transepts on 1863. The aisle walls were raised in the early fourteenth century to allow the insertion of larger Decorated style windows.