Hens Castle is one of the oldest mortared castles and oldest fortresses in Ireland. The castle takes up almost the entire island. It had a troubled history, being stormed and besieged many times, the most celebrated of these times was when the Pirate Queen Grainne Mhaol (Grace O’Malley) personally defended it. It continued to be occupied as a castle until it finally succumbed to the Cromwellian soldiers in 1654.
In the nineteenth Century this historic ruin was vandalized and hundreds of its stones were removed to build houses in the area. The interior is now a mass of stones and weeds, but it is still a very impressive sight.