Porth-y-Twr, or 'Tower Gate', forms the principal entrance from the borough of St Davids into the Cathedral Close. The defensive gate was probably added to a late thirteenth century two storey octagonal bell tower in the fourteenth century. The bell stage has large pointed openings with hoodmoulds and there are studed plank doors to the lower stage. The gateway and southern tower, to the south of the bell tower, were constructed from rougher rubble stone. The south end is rounded and the eastern front has a big segmental pointed arch over the roadway. The tower was restored in 1929 and several early Christian crosses and inscribed stones are housed in a lapidarium in the gatehouse.