Castle Street Canterbury CT1 2PR
This ruined castle, sitting on the southern edge of Canterbury's centre, is among the most ancient in Britain. Begun by William the Conqueror in 1070, by the late 1300s it had been overshadowed by the bigger fortifications at Dover and became a prison – by the seventeenth century it was already ruined. Today the roofless shell is surrounded by a quiet garden and inside you can climb part way up one of the towers. Walkways with helpful informations signs work their ways around the castle grounds before a narrow gateway through the stone walls takes you into the keep itself.