" Above the plaque, a skull and crossbones once completed the composition. The bones went missing sometime in the 1990s, leaving behind an oddly truncated warning. The building itself is a similarly layered thing: a plain early nineteenth-century Church of Ireland structure, rebuilt in 1819, grafted onto a medieval tower that pre-dates it by several centuries. That tower, entered through a Classical-style doorway inserted around 1710, rises three storeys and contains a spiral staircase, blocked doorways, vaulted roofing with traces of the wicker-centering used during construction, and bell-pull holes still visible in the vault. A modern carving of a sheela-na-gig, a distinctive figurative stone carving found on many medieval Irish churches, has been set into the angle of the tower during restoration work.

The parish of Crumlin was part of the royal manor of Newcastle Lyons and served as a prebend, meaning it provided income to a canon, of St Patrick's Cathedral. Its documentary history reaches back to before 1180, when a witness named Osbert Trussell appeared on deeds connected to lands in Killester; his descendants became prominent tenants on the manor and eventually took Crumlin as their surname. By 1212, a William Crumlin was paying £16 in pepper for the lands, possibly clearing arrears accumulated over several years. In 1216 the manor was held by William Fitz John of Harptree, likely descended from the lords of Richmont Castle in Somerset. The church itself was formally granted to the canons of St Patrick's in 1215. A royal visitation of 1615 found the church and chancel in a sorry state: the lead roof had been burned during a rebellion, the whole town with it, and the parishioners were too impoverished to carry out repairs. The graveyard, enclosed by a stone wall dated 1725 and sub-circular in plan, hints at an even earlier origin; archaeological work in 1998 and 1999 uncovered ditches concentric to the churchyard boundary, likely of medieval date, suggesting the site may sit within a pre-Norman ecclesiastical enclosure.

The church stands in Crumlin village, now thoroughly absorbed into south Dublin, and the graveyard contains several tombstones of note, including memorials to members of the Deane family of Northamptonshire and Gloucestershire from the late seventeenth century, and to Eliza, daughter of Maurice Cuffe of County Clare, who died in 1699. The tower itself repays a slow look: the blocked north doorway survives internally as an alcove, the spiral stair ends abruptly at roof level, and the irregularity of the upper walls points to structural changes over many centuries. The graveyard wall, the circular enclosure it traces, and the layers of building technique visible in the tower together make this a place where several distinct periods of Irish history are readable in the stonework, if not always immediately obvious from the street.