EASTHAM — The offshore waters of Outer Cape Cod, with their hidden sand bars, took so many vessels and lives that the stretch from Chatham to Provincetown came to be known as the Graveyard of the Atlantic.

Less than a decade after the Lighthouse Establishment was founded in 1789 — the first federal agency responsible for construction and maintenance of lighthouses — Highland Light in Truro became Cape Cod’s first sentinel, keeping watch over the Peaked Hill Bars. A decade later, twin wooden towers were built at Chatham.