The clover-leaf shaped St Mawes Castle is the best preserved and most elaborately decorated of the coastal fortresses, built by Henry VIII to defend the coast from invasion by France and Spain. It stands on the opposite side of the Fal Estuary from its sister castle of Pendennis. Unlike Pendennis, it has seen few changes over the centuries and still retains its original Tudor character.
Unlike Pendennis, St Mawes was not easily defended from the landward side and soon fell to the Parliamentarian forces in 1646. In fact, the governor realised it was hopeless to try to defend against an attack from the land and surrendered without a shot having been fired. St Mawes Castle was not refortified until the end of the 19th century, but was used as part of the coastal defences during the two World Wars. The two castles of St Mawes and Pendennis form the Cornish end of the chain of coastal forts built by Henry VIII, which include Portland, Deal and Walmer Castles.
The castle was constructed half way up the hillside on the eastern side of the Fal Estuary to protect the large inland expanse of water known as Carrick Roads. It was built with a central tower overlooking three large circular bastions, in the design of a clover leaf, to provide a wide area from which gun ports could cover all angles of approach to the estuary. It is one of the finest examples of Tudor military architecture, its stonework embellished with elaborate gargoyles and detailed windows. The Royal Coat of Arms is carved into the stonework above the entrance, and there are various other carved inscriptions throughout the interior of the castle.
The central tower was constructed over four floors and is entered by a bridge to the third floor. Inside the tower are various decorations including carved wooden representations of a cherub, a monk and fleur-de-lis, and the inevitable Tudor roses. The forward gun room has several cannons on display there are sockets in the walls that originally held large beams to support the tackle needed to manoeuvre the large cannon. Facilities include toilets and a shop which serves drinks and ice creams. There is level access to the castle for wheelchair users, but access to the upper floors is difficult for the disabled. Parking is available close to the entrance. St Mawes Castle is open daily throughout the year, apart from at Christmas and New Year.