Castle Rheban is situated two miles north of Athy. The castle, believed to be the burial place of a king, was once attached to the site of an ancient moat, but the two have long since been separated by the construction of the Grand Canal.
With the arrival of the Anglo-Normans and the re-modeling of Irish social structures, the barony of Rheban was created. The lord of this barony was Richard de St. Michael, who is credited with building the first castle there to act as a guard for the ford. The wars of 1641-50 saw the castle change ownership many times and since then the castle has been a ruin.
There has been considerable deterioration from the end of the eighteenth century and the present day ruins are much overgrown.