The building of Fastnet Lighthouse was an enourmous undertaking. Every granite stone used had to be cut to precises specifications and shipped to the Fastnet island from Cornwall.
The first stone was laid down in 1896.
Each of the granite stones of the tower is dovetailed into those around it, bonding the structure into a virtual monolith.
In total 2074 granite blocks, weighing from 1¾ to 3 tons, were used in the building.
In 1904, after 8 years work, Fastnet lighthouse was completed. With 49m it is the tallest and widest rock lighthouse tower in Ireland and Great Britain.