The first was a late 12th-century ringwork castle, cleverly built atop an even older rath, or ringfort. According to historian O’Conor, this early fortification likely served the Fitzgerald family as a timber castle well into the early 14th century, making practical use of the existing defensive earthworks that had protected earlier inhabitants.

About 400 metres to the southwest, a second, more substantial castle rose to prominence in later centuries. This stone fortress appears on both Noble and Keenan’s 1752 map and Roque’s 1760 map of the county, though by the time of the first Ordnance Survey map in 1838, it was already marked merely as ‘Site of Castle’. The structure played a dramatic role during the 1535 Silken Thomas revolt, when it was seized and used as headquarters by the Lord Deputy. A survey from 1540 describes it as ‘a castle surrounded by stone walls sufficiently repaired’, deemed essential for protecting the King’s subjects in the region. The Fitzgeralds regained control when Redmond Oge Fitzgerald secured a lease in 1551 for ‘the castell of Rahangan with the howses and offyces belonging to the same’.

The castle’s story came to an end around 1756, when it was demolished and its stones repurposed to build Rathangan Lodge, situated about 180 metres to the northeast. Today, the site has been transformed into a golf course, with no visible traces remaining of either medieval stronghold. These vanished fortifications remind us how the Irish landscape has been continuously reshaped; ancient raths becoming castle sites, castles becoming country houses, and eventually giving way to modern leisure facilities.