The Old Saybrook Lighthouse was originally the Lynde Point Lighthouse built in 1803 to mark the entrance to the Connecticut River. The octagonal tower was made of wood with a whale-oil lantern placed on top standing 35-feet high. By 1832, Congress appropriated funds to build a replacement, which is the lighthouse we know today. The Old Saybrook lighthouse is over double the height of the previous Lynde Point Lighthouse stretching 71-feet. The white octagonal, brownstone tower has a lantern room with 12 glass panels and a red roof. The light is sometimes referred to as the "Inner Light," while the Saybrook Breakwater Light is referred to as the "Outer Light."

Strong river currents and storms threatened to undercut the foundation of the lighthouse. In 1829, a seawall was built to counter the erosion. By 1831, the seawall had to be reinforced and widened.

The old keepers house was removed in 1966. In its place, a modern duplex was built to house Coast Guard personnel in hopes of deterring vandalism. The Old Saybrook Historical Society was opposed to the modern structure as incongruous with the historic tower.