Poolbeg Lighthouse is an active aid to navigation at the mouth of the River Liffey, near Poolbeg in Dublin, Ireland. First established in 1767, it initially operated on candlepower but this was changed to oil in 1786. It was re-designed and re-built into its present form in 1820.

The Great South Wall, at the Port of Dublin, extends from the tip of the Poolbeg peninsula more than four kilometres out into Dublin Bay. It was the world's longest sea wall at the time of its construction and remains one of the longest in Europe. It faces the newer Bull Wall, and has one of four port lighthouses at its end.