open to visitors on Fridays (morning and afternoon) during the summer months. Chancel arch The 12th-century Hiberno-Romanesque Triumphal Arch is one of the outstanding features of St Mary's Cathedral, Tuam. It is the only remaining part of the original cathedral, erected at this site during the reign of Turlough O'Connor. The Nave of O’Connor's cathedral collapsed in 1184 due to a fire, with only the stone chancel arch escaping. In the 14th century a new cathedral was built by the De Burgo family, but to the east of the old building, with the chancel arch becoming the entrance to the new cathedral. The chancel arch was blocked up by a stone-and-wooden structure, in the centre of which was placed a door. This structure remained in place for over 500 years. Thus, the chancel arch was exposed to the elements for this period, and it is remarkable that it has remained in such a good state of preservation. It was not until the 19th century that it became once again the chancel of the present cathedral. The rounded chancel arch is Hiberno-Romanesque in style, and is built of red sandstone. As there is no keystone in the arch, the columns supporting the capitals of the arch have a slight inward inclination in order to bear and support the tremendous weight of the whole structure. This means that the columns are not perpendicular, so that the space at the base of the supporting columns is wider than at the capitals. The arch which is perfectly circular, is 6.85 metres (22.5 feet) wide at the base and 4.88 metres (16 feet) high from the ground. It consists of six consecutive semi-circular arches of elaborately ornamented stonework supported on columns, which with the exception of the outside one, on each side, are semi-circular and not ornamented. The capitals are richly sculptured with a variety of interlaced traceries, something similar to those on the base of the High Cross in the Square. There are carved grotesque faces on the jambs. In the judgement of antiquary, Dr. George Petrie, "The Ancient Church of Tuam, was not only a larger but more splendid structure than Cormac's Church at Cashel, and not unworthy of the powerful Monarch to whom it chiefly owes its erection." In looking at the arch one is indeed so impressed by its dignity and beauty, that one is given a real vision of what