Cordouan Lighthouse, Gironde Estuary, France

Cordouan at low tide, when visitors walk the stone causeway across the reef to its fortified base at the mouth of the Gironde. Completed in 1611 as a Renaissance showpiece, with a royal chapel inside, it is often called the Versailles of the Sea. It was the first lighthouse listed as a French historic monument, in 1862, and became a UNESCO World Heritage Site in 2021. Boats run out from Le Verdon and Royan in season, and the landing depends on the tide.