The 1837 Ordnance Survey map clearly marks Milltown Castle at this exact location, and historical records paint a picture of what must have been quite an impressive structure. A lease from 1725, preserved in the Registry of Deeds, makes reference to both “the castle of Miltown” and a “new dwelling house”, suggesting the site had already seen centuries of development by that point.

The castle seems to have survived in relatively good condition into the early 20th century. When the antiquarian Fitzachary visited in 1901, he found it still in good repair and recorded some fascinating architectural details in his writings for News and the Dublin Lantern. He described it as a castellated mansion complete with an arched guardroom, an old stone staircase, and walls that measured an impressive five feet thick; these defensive features suggest the building retained much of its original medieval character despite later modifications.

Today, not a single trace of Milltown Castle remains visible above ground. The transformation of the site into a convent appears to have completely erased this piece of Dublin’s castellated heritage, leaving only the documentary evidence to tell us what once stood here. It’s one of those curious cases where a substantial building, which survived for centuries and was still standing within living memory, has been so thoroughly removed that you’d never know it existed without consulting old maps and archives.