At 6 Mary's Abbey, on the north side of the Liffey, an excavation uncovered the kind of find that archaeologists note carefully and passersby rarely hear about: the remnants of a medieval wall foundation, still recognisably old, still holding its shape after centuries underground.

The excavation took place in 2003, and what emerged was a wall foundation measuring 1.1 metres in width and surviving to a height of 0.5 metres, composed of large, undressed roughly rectangular blocks. Undressed stone, in this context, means the blocks were used more or less as they came, without being shaped or finished by a mason's chisel, which gives some indication of the practical, utilitarian nature of the original construction. The foundation stood at least two courses high. A separate wall at the rear of the site, surviving to street height, also appeared to be composed of medieval masonry. The findings were recorded by archaeologist A. Hayden, published in 2006. Mary's Abbey itself has a long history as a monastic site, and the discovery of medieval fabric within the plot is consistent with the layers of occupation that characterise this part of the city.

The site sits in an area of Dublin that repays slow, attentive walking. Mary's Abbey is a short street running between Capel Street and the broader grid of the north city, and the surrounding neighbourhood still contains fragments of earlier urban patterns if you know to look for them. The remains themselves are not publicly visible; they were uncovered during excavation and recorded rather than preserved in situ for display. What the site offers, then, is less a visual experience than a reminder that the street-level city is only one version of what is here, and that the ground beneath this particular address has been built on, and built over, for a very long time.