Cromwell's Castle

Impressive botanical garden with a range of Mediterranean and sub-tropical plants growing healthily outdoors. Created in the 19th century in the ruins of a Benedictine Abbey, with tall hedges and landscaping as windbreaks. Includes "Valhalla", a collection of sailing ship figureheads.

Burial Chamber dates from the Bronze Age, as the gradual flooding of Ennor forced inhabitants onto higher ground. It was empty when first excavated in 1900. St Mary's has some 80 similar "entrance graves", e.g. at nearby Innisidgen and at Porth Hellick Down on the east tip, but Bant's Cairn is the finest. A little lower down the hill is Halangy Down Ancient Village, occupied from the Iron Age into Roman times, with a prehistoric terraced field system. The cairn and ancient village are at the north end of St Mary's, the bus runs to the top of Telegraph Rd. They're always open, free.

The Spanish Armada was defeated in 1588, but they might come back for revenge, so fortification began here (abandoning the less-well-sited Harry's Walls). Enter the curtain wall via the Gatehouse; the powder magazine here has a free exhibition on the history. A circuit along the walls is a pleasant one hour walk, past artillery emplacements and redoubts; mostly firm easy going but some rough spots. Imposing Hugh House was the officers' quarters. The core of the Garrison, a stout Vauban-style bastion, is now the Star Castle Hotel.

These are the walls of an unfinished artillery fort built to the east of the harbour in 1552-53. Building was abandoned when they decided instead to fortify the headland to the west, which became The Garrison.

It's an ill wind: the gales of winter 1962 unearthed Romano-British remains, so where to house them? This museum, opened in 1967, displays the history of the islands. Pirates, longitude, wildlife, it's all here.