The central monument of Tlachtga itself is an impressive earthwork. Measuring approximately 135 m in diameter from outside of bank to outside of bank, it is also surrounded by a scarping (presumably providing some of the material from which the outer banks were constructed) to an additional width of c. 15 m around the entire circumference. The number of known quadrivallate enclosures is very low, and includes Rathra, Co. Roscommon (http://goo.gl/maps/aPjif), the Rath of the Synods at the Hill of Tara and the enclosure at Rathdrinna, Co. Tipperary, currently the focus of an excavation project (http://www.facebook.com/Rathnadrinna). Tlachtga differs markedly from Rathra and Rathdrinna in that the majority of the monument is taken up with its vallations leaving little room for a large interior space. The central mounded portion at Tlachtga measures c. 50 m in diameter, significantly more than a third of the total diameter of the monument. This is closer to the situation at the Rath of the Synods, where the total monument diameter is c. 85 m while the inner enclosure is approximately 32 m in diameter.