Selskar Abbey is a 12th-century structure that replaced a pre-Christian temple dedicated to Odin. The complex, which is part of the Westgate Heritage Tower, was the location where the first Anglo-Irish treaty was signed. In 1172, Henry II also spent Lent at the abbey, as he did penance for having Thomas Becket beheaded.
After years of suppression, the abbey was destroyed by Oliver Cromwell in 1649. The present Protestant church was built in 1826.