[6] St. Mary's was completed in 1210 and was founded by William Marshal, 1st Earl of Pembroke or his wife Isabel de Clare, a daughter of Strongbow.

[7] Divine Service was performed at St. Mary's until 1811 or 1812, when the west aisle was demolished to make room for the modern church.

The chancel has an aumbry, sedilia, piscina, tomb canopy and two doorways: one transitional and one Gothic.

The old chancel and the north and south transepts contain one of Ireland's largest collections of medieval funerary.

One features a cross with Lamb of God, symbolism associated with the Knights Templar.