Test excavations carried out by archaeologist Brenda O'Meara revealed the foundations of a boundary wall running between the rear yard of No. 45 and a long narrow yard to the south of the neighbouring courthouse. What makes this modest stretch of subsurface masonry noteworthy is what lies beneath it: a stepped stone foundation, almost certainly medieval in origin, indicating that the wall was built not from scratch but on the remnants of an earlier building altogether.

The site sits at a particularly layered corner of the city. The courthouse immediately to the north incorporates Grace's Castle, a 15th-century urban tower house, the kind of fortified townhouse that wealthy merchants and civic figures built within Irish towns during the later medieval period. The early 19th-century house at No. 45 Parliament Street stands just beside it. Somewhere below the yard between them, the medieval foundation survives, though it has not escaped entirely intact. A substantial stone-built culvert, running north to south and probably dating from the 18th century, cuts directly through the foundation, a reminder that later generations were as willing to bury the past as to build on top of it. The culvert would have served to channel water or drainage through what was, by then, a functioning urban backyard rather than any kind of monumental space.

The excavations were small in scale, testing rather than opening up the ground, and much of the medieval building these foundations once supported remains uncharacterised. The boundary wall itself, the visible prompt for the investigation, turns out to be the least interesting thing about the spot.