Access to the central island occurred over a drawbridge, through a pair of gatehouses on the eastern side. Caerphilly Castle's Inner East Gatehouse, based on the gatehouse built at Tonbridge in the 1250s, reinforced a trend in gatehouse design across England and Wales. Sometimes termed a keep-gatehouse, the fortification had both exterior and interior defences, enabling it to be defended even if the perimeter of the castle was breached. Two huge towers flanked the gatehouse on either side of an entrance that was protected by portcullises and murder-holes. The substantial size of the gatehouse allowed it to be used for accommodation as well as defence and it was comfortably equipped on a grand scale, probably for the use of the castle constable and his family. Another pair of gatehouses protected the west side.