County Louth is home to St. John’s Castle on the southern shores of Carlingford Lough. Built by the Norman knight Hugh De Lacy in the 12th century, this dramatic fortress offers stunning views across the Lough towards the Mourne Mountains. This is a “D” shaped castle with enclosure walls and was the first stone structure built in Carlingford. This castle and Greencastle, built on the other side of the Lough, enabled the Normans to control the entrance to the Lough. It is reputed that King John stayed here for 3 days in 1210.