Square and hulking Bunratty Castle is only the latest of several constructions to occupy its location beside the River Ratty. Vikings founded a settlement here in the 10th century, and other occupants included the Norman Thomas de Clare in the 1270s. The present structure was put up in the early 1400s by the energetic MacNamara family, falling shortly thereafter to the O’Briens, kings of Thomond, in whose possession it remained until the 17th century. Admiral Penn, father of William Penn, who was the Quaker founder of the US state of Pennsylvania and the city of Philadelphia, lived here for a short time.