Portland Head Light, Historic lighthouse in Cape Elizabeth, United States

Portland Head Light is a stone lighthouse in Cape Elizabeth, Maine, rising 24 meters (80 feet) above the coastline. The white cylindrical tower carries a black lantern room and stands on a rocky ledge at the entrance to Portland Harbor.

Construction began in 1787 under George Washington's directive and was completed in 1791, making it the oldest lighthouse in Maine. During the Civil War the tower was raised 20 feet (6 m) to improve visibility for ships entering Portland Harbor. In 1883 it was shortened by 20 feet, but mariners' complaints led to the former height being restored in 1885.

The keeper's house, built in 1891, stands beside the tower rather than at its base and now holds a museum of lighthouse history run by the town of Cape Elizabeth. Since 1998 the light has marked the finish line of the Beach to Beacon 10K road race, which starts at Crescent Beach State Park.

Fort Williams Park offers daily access to the grounds from sunrise to sunset, while the tower itself remains closed to the public. The park includes paths along the coastline that provide good views of both the structure and the cliffs.

The beacon uses a DCB-224 airport light visible for 24 nautical miles, flashing every four seconds to mark the entrance. This aviation technology was adapted for maritime use rather than developed specifically for lighthouses.