Beneath the ordinary surface of this urban neighbourhood, and just south of the street itself, once lay a millpond that fed a pair of water mills known as the Double Mills. That a working industrial site of this kind could vanish so completely into the city fabric, leaving behind little more than a street name as a clue, is precisely what makes the spot worth a second thought.

The mills had their origins in monastic ownership. They belonged to St Thomas's Abbey, an Augustinian house founded in medieval Dublin, before passing into secular hands during the upheaval of the Dissolution of the Monasteries. In 1544, they were granted to William Brabazon, a prominent figure in Tudor Ireland who served as vice-treasurer and helped administer crown lands following the suppression of the religious houses. By 1610, records confirm that two mills were operating on the site, a detail noted by Clarke in 2002 and consistent with earlier mapping evidence. The designation "Double Mills" reflects this pairing, and the millpond that powered them sat just south of the line now traced by Mill Street. A water mill of this period would typically have used a millrace to channel water onto a wheel, driving grinding stones used for processing grain.

There is nothing to see at the site itself today in the conventional sense; no surviving structure marks the location, and the millpond is long gone beneath later development. What remains is the street name and the historical record. Visitors with an interest in the medieval and early modern city can use Mill Street as a starting point for exploring the wider Liberties area, where the dense layering of ecclesiastical, industrial, and civic history is unusually concentrated. The general area around Thomas Street, where St Thomas's Abbey once stood, gives some further context for how this part of Dublin was shaped by monastic landholding before the Tudor confiscations remade the landscape entirely.