Rochester Castle stands on the east bank of the River Medway, in Rochester, Kent. It is one of the best-preserved castles of its kind in the UK. There has been a fortification on this site since Roman times (c AD43), though it is the keep of 1127 and the Norman castle which can be seen today. With the invention of gunpowder other types of defence became more appropriate, and the military centre of the Medway Towns moved to Chatham.