[5] Armagh's claim to the primacy of Ireland was formally acknowledged at the Synod of Ráth Breasail in 1111.

It was renovated and restored under Dean Eoghan McCawell (1505–1549), having suffered from a devastating fire in 1511 and being in poor shape.

[citation needed] Following the Nine Years' War, Armagh came under English control and the town began to be settled by Protestants from Britain, as part of the Plantation of Ulster.

[7] The cathedral was substantially rebuilt between 1834 and 1840 by Archbishop Lord John George Beresford and the architect Lewis Nockalls Cottingham.

The capital decoration of the two westernmost pillars of the nave (either side of the West Door internal porch) are mediaeval as are the bulk of the external gargoyle carvings (some resited) of the parapet of the Eastern Arm.

Cottingham's intention of retaining the richly cusped West Door with flanking canopied niches was over-ruled.

There are works by Francis Leggatt Chantrey, Louis-François Roubiliac, John Michael Rysbrack, Carlo Marochetti and others.