The largest Norman keep in Europe by footprint, built on the base of the Roman Temple of Claudius — you can descend into the Roman vaults beneath. The Castle Museum holds one of the finest Roman collections in Britain: jewellery, pottery, and a striking hoard of Roman bronze objects found locally. There are also exhibits on the Civil War siege of Colchester in 1648, when the town held out for eleven weeks before surrendering.
Colchester Castle
Europe's largest Norman keep, built over a Roman temple