That detail alone sets this site apart from the ordinary run of urban excavations. The ditch, four metres wide and over three metres deep, is thought to have formed part of the moat surrounding Dublin Castle, and whatever ended up in it over the centuries, whether discarded material or something less easily explained, it offers a glimpse of life, and death, in medieval Dublin that the street above gives no indication of.

Two seasons of excavation in the early 1990s, carried out by M. Byrne and reported in 1993 and 1994, gradually pushed the chronology of the site back several centuries. The 1992 dig at 26 to 29 Castle Street and 20 Lord Edward Street focused on deposits from the thirteenth to early fourteenth centuries, uncovering post-and-wattle structures, the kind of construction in which upright timber posts support a woven framework of thin branches plastered with daub, along with associated floor surfaces. Finds recovered included stick pins, arrowheads, knives, needles and combs, the small portable objects of everyday domestic life. The following year, excavation of the same plot revealed earlier occupation layers running from the tenth to the thirteenth century. These structures were all rectangular in plan, averaging around 8.2 metres in length and 3.5 metres in width. Alongside them were a large number of unlined cesspits, which, while unglamorous, proved archaeologically valuable: their fills preserved an extensive range of faunal and botanical remains that can tell researchers what people were eating, which animals were kept nearby, and what plants grew in or around the settlement.

The site itself is not marked or publicly accessible in any formal sense; it lies beneath a long-developed part of the city close to Dublin Castle, and nothing visible above ground records what was found there. For anyone walking that stretch of Castle Street, the value is in knowing what the ground once held. The excavation reports, published through the work of M. Byrne, are the primary record, and the National Museum of Ireland would be the logical starting point for anyone wanting to follow up on the finds themselves.