St Agnes lighthouse

St Agnes lighthouse is a Grade II* listed lighthouse built in 1680 for Trinity House, with a cupola added in 1806. The structure is made of colourwashed render on granite rubble, featuring a cast-iron and glass cupola. It has a circular plan and stands three storeys tall, topped by a fourth-storey cupola. The exterior includes two plat-band divisions, randomly-placed casement and four-pane openings, and projecting eaves with a cast-iron railing. The cupola has curved stanchions that support the glass structure, which is capped with a curved conical roof.

An addition from around 1840 includes a single-storey lean-to porch and corridor, along with a right-angled corridor leading to the associated house. Inside, the lighthouse features a lantern that is accessed by a wooden newel stair from the first floor, supported by a shallow stone vault that replaced the original timber ceiling. There is also a stone mural stair to the first floor, which includes four gun ports.

Historically, the lighthouse was built by Captain Hugh Hill and Captain Simon Bayly, who also constructed the Lowestoft lighthouse in 1676. It was superseded in 1910 by the Peninnis Lighthouse on St. Mary's. The original iron cresset from the lighthouse is now located in Tresco Gardens.