Location: Tresco in the Isles of Scilly, England.
Condition: Substantially intact.
Ownership / Access: English Heritage. Open to Public.
Opening times: Check their website for more info.
Price of admission: Check their website for more info.
Notes: Cromwell's Castle is a 17th-century fortification ("blockhouse") on the island of Tresco in the Isles of Scilly, built after the invasion of the Isles by Sir Robert Blake in 1651. It was further expanded in 1739 during the War of Jenkins' Ear. In the 21st century, the castle is controlled by English Heritage and operated as a tourist attraction. It is protected by law as a Grade II listed building.
How To Get To Cromwell's Castle (Map):
Cromwell's Castle Links:Cromwell's Castle On Wikipedia
English Heritage visitor's site