Cromwell's Castle

Cromwell's Castle is a circular stone tower rising about 15 meters high on a rocky promontory, built with thick walls and multiple gun ports. The structure overlooks New Grimsby harbour and was constructed entirely from stone to defend against approaching vessels.

Sir Robert Blake built this defensive tower between 1651 and 1652 after parliamentary forces took control of the Isles of Scilly during the English Civil War. The new fortress was intended to secure parliamentary control over this strategic location.

The fortress demonstrates military engineering from the republican period, designed to control access to the sheltered harbour below. Walking around it today, you can see how the gun ports were positioned to monitor approaching vessels.

Access is via a footpath along the shoreline and is available year-round during daylight hours. It is advisable to wear sturdy shoes and be aware of the tides, as the path runs along rocky ground.

The castle walls are four meters thick and were partly built using stones taken from the nearby King Charles's Castle. This recycling of materials shows how the earlier fortress became a practical resource for the newer structure.

Location: Tresco

Website: https://english-heritage.org.uk/visit/places/cromwells-castle

GPS coordinates: 49.96220,-6.34948

Latest update: December 10, 2025 20:00