The Spanish Arch is thought to be an extension of Galway's medieval city walls, designed to protect ships moored at the nearby quay while they unloaded goods from Spain. It was partially destroyed by the tsunami that followed the 1755 Lisbon earthquake. Today it reverberates with buskers and drummers, and the lawns and riverside form a gathering place for locals and visitors on sunny days, as kayakers negotiate the tidal rapids of the River Corrib. A 1651 drawing of Galway clearly shows its extensive fortifications, but depredation by Cromwell and William of Orange, and subsequent centuries of neglect, saw the walls almost completely disappear. One surviving portion has been cleverly incorporated into the modern shopping mall Eyre Square Centre.