The Castle can be visited
Rochester Castle

In the English city of Rochester stands Rochester Castle, a castle ruin. The medieval complex, located directly at a ford of the River Medway, is known for its massive keep and its strategic importance from the 12th to the 16th century.
History+
Construction of the castle began around 1127 under the direction of William of Corbeil, then Archbishop of Canterbury, with the support of King Henry I. The keep's design was based on the great Norman castles of that era, comparable to sites like Dover Castle or the Tower of London.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Maciek Wegrzyn
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 51.3894, 0.5013