Address: ME1 1SW
Website: English Heritage
The keep was built by the Archbishop of Canterbury, William de Corbeil and it is one of the largest keeps in England.
There is a fantastic example of well-shaft that was re-built in 1826 (see if you can spot it in the photo gallery above).
Fantastic fireplaces and grand arches can be seen on some of the floors that you can access by climbing up/down the spiral staircase.
You can explore the grounds free of charge but there is a small charge if you want to explore the keep (which I thoroughly recommend) but if you are an English Heritage member then you can get in for free.
