Though no longer marked on Ordnance Survey maps, local tradition maintains that a castle once stood at a point called “Cashlan” on the hill, and the site’s rich documentary history suggests this wasn’t merely folklore. The Cromwells, an early English family in the area, likely took their name from this very place, recorded as “Cromehoill” or Cromellston as far back as 1299. By 1583, it was described as “Knockgromell, a poor, low castle or peel tower”, suggesting a modest defensive structure rather than a grand fortress.

The castle’s ownership reads like a who’s who of Anglo-Irish history, passing through various hands over the centuries. Records from 1591 show it being transferred from W. Agar to W. Carter, whilst in 1607 it went to N. Haward. Perhaps most intriguingly, in 1637 it came into the possession of Francis Fitton of Anny through his marriage to J. Lacy; Fitton was described rather bluntly in contemporary documents as “a distracted lunatic and non compos mentis”. The castle appears to have survived at least until the late 17th century, as it’s clearly depicted as a tower house on the Down Survey map under the name “Crumlin”, and James FitzGerald of Cromwell was attainted there in 1688.

Despite this wealth of documentary evidence, the castle has completely disappeared from the physical landscape. When surveyed in 1943, investigators could find no trace of any structures, and modern aerial photography confirms its absence. The site was eventually sold to B. Burton in 1703, by which time the castle may have already been in ruins or demolished. Today, only the place name and persistent local memory preserve the echo of what was once a modest but strategically positioned tower house, watching over the Limerick countryside for nearly four centuries.