The article describes a royal seat on the Rock in the 4th century, but most surviving buildings date from the 12th and 13th centuries. The round tower, dated to about 1100, is the oldest and tallest structure at 92 feet (28 m), with its entrance about 12 feet (3.7 m) above ground. Cormac's Chapel was begun in 1127 and consecrated in 1134.
The chapel is mainly sandstone and Romanesque, with a barrel vault, arcading and carved tympanums. Twin towers flank the junction of nave and chancel, a Germanic feature the article credits to carpenters from Regensburg. It holds the only surviving Romanesque frescoes in Ireland, which waterlogged sandstone has damaged.
The cathedral, built between 1235 and 1270, is aisleless and cruciform, with a residential tower house at the west end. The Hall of the Vicars Choral dates from the 15th century. Cormac's Chapel is open for limited tours only.

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