That gap between the age of the ground and the age of the walls is the quietly interesting thing about St. Munchin's Church of Ireland church. The tradition credits its foundation to St. Mainchin, son of Sedna, who lived around 480 to 500 AD, making him a near-contemporary of Patrick. Scholars regard that particular claim with some scepticism, and the more likely history is that a formal Christian church was established here during the tenth or eleventh century, when Limerick was a Hiberno-Scandinavian settlement, a town shaped by Norse settlers who had converted to Christianity and built their own urban fabric along the Shannon.

By 1201 the church appears in the historical record under the Latin form "Ecc. Sci. Manchini", and in 1204 to 1206 Bishop Donatus O'Brien named it among the diocesan prebends, meaning it was attached to a cathedral canonry and carried an income. It had, for a time, served as the cathedral of the Ostmen, the Norse townspeople, before St. Mary's Cathedral displaced it in that role. Later centuries brought slow accumulation rather than drama: in 1445 a Limerick merchant named Geoffrey Galwey left 6 shillings and 8 pence to the church in his will; in 1711 Bishop Smyth oversaw repairs; and in 1752, officers of the 39th and 44th regiments, Colonel Aldercron's and Sir Peter Halket's men, paid for a gallery at the west end. By 1827 the old building, a plain structure 86 feet long and 23 feet wide, had deteriorated to the point where rebuilding was necessary. The new church was funded partly by the Board of First Fruits, a body established in 1813 to finance Church of Ireland building works across Ireland, and designed by James Pain, who served as the Board's architect for the Munster region.

The present four-bay church sits on a limestone outcrop with the churchyard, 630 feet in circumference according to an 1827 account, hanging over the Shannon to the west. The old town wall forms its northern boundary, and a terrace walk along it looks across towards Thomond Bridge and County Clare. Access from Castle Street passes through a pointed-arch gate and down a narrow lane, the kind of approach that makes the sudden openness of the churchyard feel abrupt and welcome. Inside the grounds, recumbent stone grave markers and table-tombs from the eighteenth and nineteenth centuries are spread among more elaborate funerary monuments. Among the recorded monuments are those of Elinor, daughter of Thomas Young, dated 1649, Thomas Smith, 1711, and Major James Buchanan, 1778. The location, with King John's Castle and Thomond Bridge visible nearby, means the site sits within a cluster of medieval and early modern landmarks that reward a slow, unhurried look.