Old Kilcullen, formerly Kilcullen, is a townland in County Kildare, Ireland, which includes a noted religious archaeological site within its boundary. As a townland it is relatively large but lightly populated. The location of the townland is roughly contained within the R418 and R448 routes starting at its most northerly point, a crossroads known locally as Thompson's Cross. The townland continues south from this point as far as Harklow and is intersected in its north east corner by the M9 motorway at Abbeyaun. Old Kilcullen was formerly the site of a walled town, and before that of an ecclesiastical settlement dating from the 5th century. The original settlement gave its name to the substantial surrounding civil parish and barony.

Irish round towers are early medieval stone towers of a type found mainly in Ireland, with two in Scotland and one on the Isle of Man. As their name Cloigtheach indicates, they were originally bell towers, though they may have been later used for additional purposes.