was erected on the tower's roof. The wider site was developed into a modern radio transmitting and communications site by the late-C20. The tower is now a private residence. It was at this tower about 1898 that Guglielmo Marconi heard wireless signals transmitted from Porthcurno, a distance of 30 miles. It was used by Radio Scilly for broadcasting. Note: To strengthen Scilly's defences Major Daniel Lyman proposed the construction of three gun towers in 1803, each armed with a 32-pounder carronade on top. The presence of three towers on St Mary's, in the heart of the Garrison, on Buzza Hill and at Newford Down, has led some writers to link them to Lyman's proposal. However, his proposal was never enacted, and the three towers have different origins. Harry's Walls Harry's Walls are the remains of an unfinished artillery castle situated on a hilltop to the north-east of Hugh Town. It was begun in 1551 as part of a major phase of fortification on the Isles of Scilly, undertaken to counter threats from the French. It was left unfinished because the site was recognised to be unsuitable. Giant's Castle Giant's Castle is an Iron Age cliff castle on the coastal path between the airfield and Porth Hellick Bay. The Garrison and Star Castle Star Castle is at the centre of a fortification system around the west side of St Mary's known as the Garrison. The walls of the castle take the shape of an eight-pointed star. It comprises an outer wall around the outcrop of Hew Hill, protecting the town and the castle, with strategically placed gun batteries at regular intervals around the outer wall, allowing covering fire at all angles. A redundant windmill was converted after 1831 into Garrison Tower as a lookout tower for HM Coastguard. The Star Castle was built in 1593 by the Surveyor of the Royal Works and mapmaker Robert Adams (d.1595), under the direction of Francis Godolphin, following the Spanish Armada of 1588. Fearing another Spanish invasion, in May 1593 Queen Elizabeth I ordered the construction of a fort and two sconces as a lookout for any intruder ships. In 1740 Master Gunner Abraham Tovey transformed the Garrison building walls with gun batteries, including Colonel Boscawen's Battery, in a circular shape following the coast line of The Hoe. Star Castle is now a hotel. Peninnis Head The 14 metre metal tower lighthouse on Peninnis Head