Carisbrooke Castle's medieval gatehouse. Carisbrooke has been a central place of power and defence on the Isle of Wight for over 1,000 years. The keep and main walls were built soon after the Norman conquest, and the castle was frequently updated over the centuries. Under the threat of Spanish invasion in Elizabeth I's reign it was transformed into a state-of-the-art artillery fortress. During the Civil War it was used as a prison, most famously housing Charles I. The castle also served as a magnificent residence for the lords and governors of the Isle of Wight.