Little Mark Island Monument is a rare Maine coastal beacon on a small island in northern Casco Bay that combined navigation with lifesaving use. Built in 1827 as a functional replica of an 1811 structure at Cape Elizabeth, it is one of only three pyramidal stone beacons of its kind ever built in the state. The slender square stone pyramid, likely made from rock quarried on the island, originally sheltered supplies for shipwreck survivors who reached shore. A light added in 1927 turned the old day beacon into an active marine light, now operated by the U.S. Coast Guard, preserving an early nineteenth-century design in modern service.