They were all built soon after the Battle of Hastings, on the main Roman road from Dover to London.

[2] A wooden motte and bailey castle were erected in 1066 - its motte may be the mound which is still visible in the Dane John gardens near the stone castle (which may, in turn, be a Roman burial mound), with Dane John deriving from donjon.

The great stone keep was largely constructed in the reign of Henry I as one of three Royal castles in Kent.

It is mainly made of flint and sandstone rubble.

The Governors were responsible for the upkeep and security of the castle, which passed into private hands at the end of the reign of King James VI and I (1625).