Portland Bill is a narrow promontory at the southern tip of the Isle of Portland and the southernmost point of Dorset. The geographical curiosity with its shallow reefs and ledges, sandbanks and strong tidal races is a notorious shipping hazard.

Over the centuries it has been the location for three lighthouses with the current operational one first lit in 1906. The stone obelisk was added by Trinity House in 1844 to warn of a low shelf of rock extending 30 metres out to sea.