The Abbey at Cross was probably used originally as a resting-place for monks travelling to and from the island of Inishglora. It was said that the rocky spit about a mile south of the Abbey went much closer to Inishglora in the distant past and that, at low tide, only a plank was needed to gain access to the island. Later a rope ferry was used. By 1198 the monks had left Inishglora and come ashore to Cross, possibly through fear of Viking raids. From the early 13th century Cross was a branch of the Augustinian Abbey of Ballintubber. The present church, of which little more than the east gable and window remain, was built about 1219, but it was probably built on the site of a much older church. Under Queen Elizabeth, Cross was suppressed and the monks banished. Under James I, in 1615, the land was granted to one Arthur Savage.
The Lighthouse was built in 1864 and finished in 1865. Lighthouse itself is unique in Ireland because of its square shape. From 1969 to 1972 it served as a post office with its keeper both in charge of the lighthouse and a postmaster. The lighthouse even served as a weather station until 1957 and on June 1944 a weather report was sent from Blacksod which influenced the go ahead of the D-Day landings. In 1974 Blacksod was made fully automatic.