1811: Bell Rock Lighthouse

Bell Rock Lighthouse, the world’s oldest surviving sea-washed lighthouse, has saved countless lives over the past two centuries. Located on the east coast of Scotland, it was built to alert seagoers to the dreaded Inchcape Rock, 11miles out from Arbroath Harbour.

The need was urgent. According to some reports, fear of hitting the treacherous rock was so great, that more ships were shipwrecked on its

neighbouring shores than on Inchcape in their attempt to avoid it.

Constructed by Robert Stevenson in 1811, the lighthouse posed huge engineering challenges at the time. Because of its position, the surface of the rock was exposed only at low water, while at high water it was submerged to depths of up to 16 feet (4.9m).

The method of trenails and wedges was carried out so that the lower part of the lighthouse would remain upright when covered by high tides. Each stone had two circular holes for trenails to pass through and continue six inches into the already-laid stone below.