This Town Castle is Galway's best example of a fortified house, built by the prosperous Lynch family in the 16th century as protection from the raids of the chieftains of the 14 Tribes. Spanish decorative motifs are visible on its stones, along with decorative windows and the Lynch family coat of Arms.
The Lynches were a wealthy family, many of whom served as Galway mayor. One of the mayors, James Lynch Fitzstephen, actually pronounced his own son guilty of the murder of a Spanish sailor who became involved with a female family member in 1493. Lynch hanged his son Walter himself when everyone else refused to participate. The term 'Lynch Law' arose from this unfortunate episode. The old prison on Market Street in Galway city displays a black marble plaque marking the actual spot of the execution.
A branch of the Allied Irish Bank is now located on the premises of Lynch's Castle, and the small museum located inside can be visited whenever the bank is open.