Ross Castle in Killarney

You're standing at Ross Castle, on the edge of Lough Leane, the big lake in Killarney National Park. Start with the tower. This tower house was built in the late fifteenth century by the O'Donoghues, the clan that ruled this area back then. A tall stone tower like this was typical for Irish chieftains in the Middle Ages. See the square turrets on two diagonally opposite corners? They were there for defence. Originally a square wall surrounded it all, with round towers at the corners.