English Heritage: Cromwell's Castle
The tall round tower of Cromwell's Castle is one of the few stone fortifications that survived the Interregnum (1649–60), taking it's name from Oliver Cromwell, Lord Protector of England. Dating back to 1651, the castle was built to protect Bryher and Tresco.
The castle can be found right on the shoreline, north of New Grimsby harbour and is only accessible on foot. Sturdy footwear is recommended as there is a hillside of heather to walk through and steep stones up to the castle's towers.
There is a well-stocked shop just south of New Grimsby harbour where you'll be able to find refreshments. The castle is free to visit and dogs are also welcome on a lead.