This light is known by several other names: Fort Constitution Light, Fort Point Light, and Newcastle Light. The 48 foot cast-iron tower was built in 1877 and still shines through a flashing green fourth-order lens. The keeper's quarters are within the walls of the old fort.
Portsmouth Harbor Light was the site of one of the 12 original Colonial towers, with a light dating from 1771.
Fort Constitution is now a Coast Guard Base. The old fort and the lighthouse are open for visitors during the day, but only if you walk on the blue line that winds through the base to the water's edge.