The most impressive monument in Colchester is also its oldest: the magnificent keep of Colchester's Norman Castle, built in 1070-1080. But its history goes back much further, as the castle is built on the foundations of the Temple of Claudius.

This was the centre of the cult of the divine emperor in Britain, and was dedicated to Claudius in 54 A.D. It would have been the most impressive Roman temple in Britain, and was still an impressive sight in Saxon times.

Colchester claims to be Britain's oldest town, and it was indeed already a major settlement for the Celtic population when the Romans invaded in A.D. 43. They established a legionary fortress there, and as they moved on this was converted to a settlement for retired legionaries and their families. As well as the huge temple, it boasted a monumental arch, a major Roman theatre and a huge Circus (chariot race track). But it had no defensive walls.

This meant that when Boudica began her famous revolt against Roman rule in 61 A.D. Colchester was extremely vulnerable. The revolt started with the Norfolk-based Iceni tribe, but the local Trinovantes enthusiastically joined in, and a substantial army marched on Colchester, seen as a major seat of the hated Roman rule.

The Roman legions were scattered across Britain, with the largest force campaigning in Wales. Just a few hundred auxiliaries in London were available for defence, so Colchester was left to fend for itself. The veterans would have taken up their old weapons and done their best for their families. The sources record that they fell back on the incomplete Temple of Claudius. As this had no windows the women and children would have been placed inside while the men defended the temple steps.

This defence must have been stubborn, because they held out for two days against Boudica's warriors. Numbers prevailed in the end however, and the entire population of Colchester was slaughtered. The town was burned to the ground, and a thick black layer of ash remains to this day under buildings within the perimeter of the Roman town.

Boudica went on to sack London and St Albans, destroying a large part of a Roman legion in the process. An estimated 70,000 people died in the revolt, but the Governor Suetonius gathered an army and defeated Boudica in a bloody battle whose location is still debated.

Colchester was rebuilt, with the belated addition of sturdy walls of which substantial remains can be seen to this day.

Excavation of the foundations of the castle has revealed vaults under the floor of the original Roman temple. It is possible to stand in these and imagine overhead the clash of arms and the screams of the defenders, desperately holding out for relief which never came.