In addition to the different forts scattering the island there were originally four Martello Towers also built on the island. Two of these still remain and can be easily visited. Cloughland Martello Tower which lies on the eastern side of the island is in a fairly ruinous state but Ardagh Martello Tower was restored as part of a tourism project and is in quite a good condition.
Ardagh Martello Tower
Cloughland Martello Tower