Long Island Viaduct, Road bridge in Boston Harbor, Massachusetts, US

The Long Island Viaduct was a steel truss bridge opened in 1951, carrying a road deck on rust-streaked concrete piers between Long Island and Moon Island in Boston Harbor. Its deck had a metal railing and tall curved streetlights, and a large square concrete pier with a rectangular opening stood at one end. The bridge was demolished in 2015, leaving the foundations.

The bridge was built to provide access to Long Island, where important medical facilities operated. Massachusetts authorities ordered the permanent closure of the viaduct in 2014 after structural safety concerns made it unsafe for travel.

Throughout its operational years, the viaduct provided access to multiple healthcare facilities, including a hospital for chronically ill patients until 1983.

The viaduct provided a single travel route across the bay with sufficient width for regular vehicle traffic. Access to the bridge was gained through a causeway extending from Moon Island toward the Squantum area.

The bridge was demolished in stages: its central span was removed and ferried away in February 2015, and the remaining spans were brought down in controlled demolitions that March and April. The concrete foundations still stand in the water.