Take the opportunity to drop by the largest medieval parish church in Ireland, the Collegiate Church of St. Nicholas, right in Galway’s historic center. When it was finished in the 1320s, it dwarfed several Irish cathedrals. Christopher Columbus visited and prayed here in 1477; almost two centuries later, British troops loyal to Oliver Cromwell set up their stables in the church during the momentous Siege of Galway, in 1652.