Today, only fragments remain of what was once a fortified manor; archaeological excavations have revealed the foundations of a single wall stretching 6.4 metres, along with evidence of a rock-cut fosse, or defensive ditch, that once protected the castle. The site sits about 400 metres from Ryland Castle across the river, placing it within a network of medieval strongholds that controlled this strategic waterway.

The castle’s history is closely tied to the Calvert family, better known for founding the colony of Maryland in North America. After passing through various hands in the 16th century, including a violent episode in 1579 when the Kavanaghs burnt the original manor, the property was purchased by Sir George Calvert, the first Lord Baltimore, in 1625. Calvert rebuilt the castle, which by 1610 was described as a bawn with two towers and a gate. His son Cecil, the second Lord Baltimore, who established Maryland as a Catholic haven in 1634, later leased the estate to London investors in the 1650s with hopes of developing an iron industry here.

Archaeological work between 2009 and 2011 uncovered more than just castle foundations. About 200 metres north of the main site, excavators found the remains of a 17th-century brick building with an attached kiln, likely a malthouse used for brewing beer. The structure’s shale-flagged floor and brick walls, though surviving only to two courses high, contained ceramics and tobacco pipes dating to the mid to late 1600s, suggesting it was abandoned by 1700. This discovery hints at the broader economic activities that once flourished around the castle, from agricultural production to early industrial ventures, making Clohamon a small but significant piece in the puzzle of Ireland’s colonial and economic history.