Portland Castle stands at Castletown on the north-east shore of the Isle of Portland, five kilometres south of Weymouth, looking out over Portland Harbour.
It was built between 1539 and 1541 for Henry VIII as part of the Device programme — the chain of coastal artillery forts thrown up when the break with Rome left England expecting invasion from France and the Holy Roman Empire.
Its purpose was to defend the Portland Roads anchorage, working in partnership with its sister castle of Sandsfoot on the Weymouth shore opposite, so that the two crossed fire over the water between them.
Visitors point this out and they are right: it is a gun fort, not a castle.
The design is a fan or segment shape, built from Portland stone quarried on the island: a curved central tower with a gun battery on the seaward face, flanked by two angular wings. Everything about it is arranged to present low, thick, sloping masonry to incoming fire and to give the guns a wide arc over the anchorage.
Shortly after completion it was armed with eleven artillery pieces, all intended for use against ships.
It is one of the best-preserved of all the Device forts, and it survives largely because it was continuously used rather than abandoned.
The Civil War. Portland was taken by Royalists for Charles I, survived two sieges, and finally surrendered to Parliament in 1646.
The eighteenth and nineteenth centuries saw it in use as a garrison, and later as a private residence with a house built alongside.
The twentieth century. Portland Harbour became a major Royal Navy base, enclosed by vast breakwaters, and the castle served through both world wars. In 1944 it was one of the D-Day embarkation points — American troops boarded here for Omaha Beach, and the slipways they used are still on the shore.
The audio guide is included and visitors specifically recommend it — a handheld device giving a spoken account room by room, which makes the fort considerably more legible than it would otherwise be.
Inside: the great hall, the kitchen, the gun rooms, the captain’s house and the roof.
The Tudor-style garden and the Contemporary Heritage Garden outside are pleasant and well kept.
The setting — the fort sits right on the water, with Portland Harbour, the breakwaters, the marina and the naval history all in view. Visitors consistently praise the surroundings as much as the building.
Time: ninety minutes to two hours.
Admission charged by English Heritage; free to members.
Parking: a car park for castle visitors.
Facilities: café, shop, toilets.
Access: the ground floor and gardens are largely accessible; upper levels involve stairs.
Getting there: Liberty Road, Castletown, Portland — about fifteen minutes from Weymouth by road, with buses.
The island is worth the day: Portland Bill with its lighthouse at the southern tip, the quarries that supplied the stone for St Paul’s Cathedral and the Cenotaph, Church Ope Cove, Rufus Castle, and Chesil Beach running eighteen miles north-west from the island’s root.
Sandsfoot Castle, the sister fort, is on the Weymouth shore and is free.
Not in the medieval sense — it is a Tudor artillery gun fort, built low and thick to mount cannon rather than to withstand a siege.
Between 1539 and 1541, for Henry VIII, as part of the Device programme of coastal forts.
Yes, included in the admission, and visitors recommend it.
American troops embarked from Portland for Omaha Beach in 1944, and the slipways survive on the shore.
Sandsfoot Castle, on the Weymouth shore opposite, which is free to visit.