The gateway of a castle was always a major weak spot in the defences, which later developed into the strongest part of a fortifications perimeter. The development in gatehouse design known as the great gatehouse has been compared in strength to the keeps of earlier castles. Using the same principles as in the gatehouse, the great gatehouse was provided with a pair of large flanking towers projecting forward from the line of the curtain wall, while two smaller flanking towers projected into the inner ward. The gatehouse was provided with a number of defences such as; machicolations, slits and battlements, the passage way itself was defended by a porticullis at each end and murder holes in the vaulted roof above. The chambers above the passage way were used to house the machinery for raising and lowering the porticullises and the drawbridge if one was provided, the rest of the remaining area was used as accommodation for the garrison or sometimes as residential appartments for the Lord or castellan of the castle. See keep gatehouse.