St. Mary's Airport, the main airport for the Isles of Scilly is located on the island.
There has been an RNLI lifeboat station on St. Mary's since 1837. The first two lifeboats were kept in a boathouse on the town beach at Hugh Town. Following closure in 1855 the lifeboat station was re-opened in 1874 and a boathouse was built on the beach at Porth Cressa. In 1899 a new boathouse and slipway were built at Carn Thomas and the first motor boat arrived in 1919.
The lifeboatmen of St. Mary's have saved many lives in the dangerous seas around the islands, and many have been awarded bravery medals for their courage.
John Wesley preached here on Tuesday 13 September 1743. The Wesleyan Methodist Society was established in 1788 and the first chapel erected in 1790. This was replaced in 1828. The present Methodist church was built in 1899 by A.J. Trenear in Hugh Town and is part of the Isles of Scilly Methodist Circuit.
Dating from 1803 it was one of three gun towers built on St. Mary's by Major Daniel Lyman. They were intended to accommodate 8-10 men and mount a 32-pounder carronade at the top. It was at this tower about 1898 that Guglielmo Marconi heard wireless signals transmitted from Porthcurno, a distance of 30 miles.
Star Castle is at the centre of a fortification system around the west side of St. Mary’s known as the Garrison. It comprises an outer wall around the outcrop, protecting the town and the castle with strategically placed gun batteries at regular intervals around the outer wall, protecting the castle from all angles.
The Castle was built in 1593, under the direction of Francis Godolphin, following the Spanish Armada of 1588. Fearing another Spanish invasion, Queen Elizabeth I ordered its construction as a lookout for any intruder ships.
The walls of the castle take the shape of an eight-pointed star.
In 1740 Master Gunner Abraham Tovey transformed the Garrison building walls with gun batteries in a circular shape following the coast line of The Hoe.
Star Castle is now a hotel.