Caernarfon, with its asymmetrically positioned towers and irregular plan, suggests the traditional castle design, which reflects the topography. But James of St. George also developed a new concentric castle plan, which had double encircling walls and an overall symmetrical, rectangular plan. Harlech brilliantly demonstrates the geometric perfection desired by Master James. Lower outer walls and higher inner walls form a square within a square, and towers rise above towers. The castle had an open inner court with the massive defenses focused on the main gate, which became the residence of the governor of the castle. A large square building with corner towers and a pair of towers that flank the portal, the gatehouse expanded from a place for guards and portcullis machinery to a full hall with private rooms, facing both the inner court and out to the country or city.
High above the bay (which is now silted in) on a sheer cliff 200 feet high, the castle at Harlech covers a small plateau. To enter the castle, the visitor had to pass through a barbican, cross over a causeway that spanned a 40-footwide ditch, pass through the outer gate, and only then arrive at the gatehouse, which had strong doors and portcullises. The gatehouse at Harlech covers an area of 80 feet by 54 feet and has three stories with an inner tower, which can be cut off from the rest of the castle. Across the inner ward from the gatehouse stands the great hall, its windows looking out to the sea. Kitchens and buttery were at one side; the chapel, work rooms, storage rooms, and well on the other. Walls down the cliff link the castle to a watergate that can be reached by narrow steps and walk, which are barred by a gate and drawbridge. The defensive system proved itself during sieges in 1404, 1408-9, and 1451-68. In the last siege, the castle garrison was starved into surrender, their heroism commemorated in the Welsh anthem, “Men of Harlech.”