By the fifteenth century stone fortifications were becoming much more common. The preferred form was the regular stone tower house with thick stone walls often with a vaulted stone ground floor (resistant to fire) a main hall at first floor level and the lord’s rooms above. The only surviving example in the Strabane area was built by the O’Neill’s on Island Mc Hugh in the Baronscourt Estate, but there was also a tower built in Strabane in 1573, one in Dunnalong (1568) and one built by the O’Donnell’s in Lifford in 1527. The O’Neills also captured one from the O’Donnells at Castlederg in 1497.