Dunguaire Castle (Irish: Dún Guaire. Dún is the Gaelic for fort and Guaire was the legendary king of Connacht) is a 16th-century tower house on the southeastern shore of Galway Bay in County Galway, Ireland, near Kinvarra.
The castle's 75-foot tower and its defensive wall have been restored to excellent condition, and the grounds are open to tourists during the summer. It is thought to be the most photographed castle in Ireland.
The castle was built by the Hynes clan in 1520, a family who may have been associated with the area since 662, when the site is believed to have once been the royal palace of Guaire Aidne Mac Colmáin, the legendary king of Connacht and progenitor of the clan. Dunguaire Castle was transferred in the 17th century to Oliver Martin, (father of Richard Martin Fitz Oliver).
It remained in his family until it was purchased in the early 20th century by the surgeon and poet Oliver St. John Gogarty. Gogarty began restoring the castle and established it as the meeting place for the leading figures of the Celtic Revival, such as W.B. Yeats, George Bernard Shaw, Augusta, Lady Gregory, and John Millington Synge.
The castle was acquired in 1954 by Christobel Lady Ampthill, who completed the restoration work started by Gogarty. It was later purchased by Shannon Development, an Irish corporation that manages numerous historic tourist attractions in Ireland. During the summer months when Dunguaire Castle is open to the public, a Medieval Banquet is held every night with costumed performers who recite Irish literature and play traditional Irish music.
Dunguaire Castle was used as a filming location for the Scottish castle home of the main character in the 1979 film, North Sea Hijack.
Part of the lore about Dunguaire's Castle is that the Lord of the castle was very generous and he continued this generosity into the afterlife. Today, if a person stands at the front gate and asks a question, they will have an answer to their question by the end of the day.