About
Cromwell's Castle guards the channel between Tresco and Bryher from a rocky projection on the shoreline. Built after Parliamentarian forces took the Royalist-held Isles of Scilly in 1651, the round tower is one of Britain's relatively few surviving Cromwellian fortifications. Its compact shape and gun platform make its defensive purpose easy to understand, while the sea and neighbouring islands provide the context that a landward photograph can miss. Visitors particularly enjoy the views from the upper level, reached by narrow, steep stone steps. The castle is accessible only on foot from the New Grimsby side of Tresco, and sturdy footwear helps on the uneven coastal approach. English Heritage describes a six-mile circular island walk incorporating this castle and other fortifications. Dogs are welcome on leads.
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- Cromwell's CastleDaylight hours
Opening times may change at short notice.
Daylight access all year. Arrange travel to Tresco separately and allow time for the walk from New Grimsby.
Only accessible on foot. The coastal footpath is uneven and the castle has steep stone steps; sturdy footwear is advised.
Dogs at the location: Allowed with restrictions. Dogs on leads are welcome at the castle.
Dog walks in the grounds: Allowed with restrictions. Dogs on leads are welcome at the castle. Normal advertised site access applies; entry is free.
Leads: Keep dogs on leads.
PricingFreeFree for all visitors
Free entry for everyone
Entry
Free for everyone
Pricing details
Free for everyone during advertised access. Any suggested donation is voluntary; parking and separately ticketed nearby attractions are excluded.
ParkingNo car park
Arrive on foot, by bike or by public transport.
Parking details
The pin uses New Grimsby Quay as an island arrival point, not a car park. Arrange island transport separately and follow the coastal approach.
Walking routes1 route
Tresco circular coastal walk(opens the full route on the National Trust site)
WalkDog access not confirmed
The official page identifies a six-mile circuit linking Cromwell's Castle, King Charles' Castle and the Old Blockhouse. Island transport is separate; rocky paths and steep castle steps.
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Checked 2026-09-14
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