Ferns castle is considered to be one of the finest examples of an Anglo-Norman fortress in Ireland. This was originally the stronghold of Diarmaid McMurrough (1110-1171). McMurrough was the King of Leinster who invited Strongbow and the Normans into Ireland in 1169 to help strengthen and save his collapsing Kingdom. The castle was built about 40 years later by the great William Marshall in 1220. It passed to the Kavanaghs, who in turn held it until 1540 after which it was staffed by a succession of English governors. Over its lifetime the castle has been sacked, damaged and modified several times. The Norman chapel inside is regarded as the finest of its kind in the country. It has a magnificent vaulted ceiling and three windows to light the interior. The castle would have originally been square with four large towers at each corner. It is still possible to climb to the top of one of these towers and enjoy the spectacular view of the surrounding lush countryside. It is only when you see this view that the strategic importance of the castle can be appreciated.