Historical records from the Down Survey of 1655-6 clearly mark a castle at what was then called ‘Moltainstowne’, providing tangible evidence of a defensive structure that once stood in this area. The survey, commissioned by Oliver Cromwell to map and redistribute Irish lands after the Confederate Wars, serves as one of our most valuable sources for understanding the landscape of 17th century Ireland.

Today, visitors to Mulchanstown won’t find any visible remains of this castle; instead, they’ll encounter the Stillorgan reservoirs that now dominate the entire townland. These Victorian-era water storage facilities, built to supply Dublin’s growing population in the 19th century, have completely transformed the medieval landscape. The construction of the reservoirs likely destroyed or buried whatever remained of the castle structure, a common fate for many of Ireland’s lesser-known historical sites during periods of industrial development.

The transformation from medieval stronghold to modern utility infrastructure tells a broader story about Dublin’s expansion and the choices made between preservation and progress. While the castle at Mulchanstown may be lost to us physically, its documentation in the Down Survey ensures that this small piece of local history isn’t entirely forgotten, compiled and preserved through the work of historians like Geraldine Stout and Padraig Clancy who continue to piece together Ireland’s layered past.