Start Point is one of twenty nine towers designed by James Walker. The lighthouse is in the gothic style, topped by a crenellated parapet. The main tower is built of tarred and white-painted granite ashlar with a cast-iron lantern roofed in copper. The tall circular tower is 92 feet (28 m) high with a moulded plinth and pedestal stage and two diminishing stages above that. There are two entrances porches, on the north and south sides. The porch on the south side is blocked and has a 4-centred arch hood mould, whilst the doorway to the north porch has a Tudor arch. Both have raised parapets with Trinity House arms. The inside of the tower includes a cantilevered granite staircase around the inside well of the tower with an iron balustrade completed by a cast-iron newel.
The lighthouse originally had the keepers’ living accommodation on the ground and first floors but this was removed in 1871 when new keepers’ houses were built, either side of the porches to the north and south. In 1882 another cottage was built, detached from the tower, to the east. All three were designed by James Douglass (though the north and south dwellings were rebuilt in the mid-1950s).
Other nearby buildings were used by the lighthouse keepers, who originally could only get on or off the lighthouse by boat, such as the well-house and piggery.