Kidwelly Castle in Carmarthenshire

You're standing at Kidwelly Castle, Castell Cydweli in Welsh. The ruin looks out over the River Gwendraeth and the little town of Kidwelly. Start with that huge gateway on the south side. That's the great gatehouse. John of Gaunt, Duke of Lancaster, had work begin on it in 1388, but it wasn't finished until 1422. Behind its twin towers sat a block of living quarters, probably for the constable.