Beneath the floor of a building at number 4, excavations uncovered not one layer of the city's past but two, stacked directly on top of each other, each belonging to a different era of urban life.

Work carried out in 1994 revealed a large brick-built cellar, the kind of functional subterranean storage space common in post-medieval Dublin, where merchants and tradespeople needed somewhere cool and dry to keep goods. That find alone would not have raised many eyebrows, but beneath the cellar floor, archaeologists encountered an older stone wall. The pottery recovered from the site dated mainly to the sixteenth century and later, placing human activity here firmly within the period when this part of Dublin was developing as a commercial quarter close to the civic centre. The area around City Hall and Cork Hill had long been significant in the life of the medieval and early modern city, and finds like these help fill in the texture of daily life in streets that have been continuously occupied, built over, and rebuilt for centuries.

The site itself is not publicly accessible or marked in any visible way; this is archaeology that exists in the record rather than on display. Exchange Street Upper is a short road, easy to walk in a minute, and most people pass through it without pausing. For those interested in the physical layers of the old city, it is worth knowing that the ground here has been read carefully, and that even an apparently ordinary building can sit above centuries of accumulated occupation. The nearby Dublin City Council offices and City Hall are open to visitors, and City Hall in particular contains a permanent exhibition on the history of Dublin that provides useful context for understanding why this small patch of ground attracted archaeological attention in the first place.