¹⁸Grogan, Eoin. The Late Bronze Age Hillfort at Mooghaun South. Ireland: Discovery Programme, 1999. 32-33.
When this small cairn, 4.3 m (14 ft) in diameter, dating from the Early or Middle Bronze Age, was excavated in 1993 it was found that the bottom course of stones rested directly on the bedrock, making it unlikely that it contained any cist burials. The cairn was likely squared off when it was re-purposed as the base of an Ordnance Survey trigonometric pillar. A viewing platform was built directly above it. (Grogan, Eoin. The North Munster Project. Vol. 1. Bray, Co. Wicklow: Wordwell, 2005. 122.)
Another remnant of a structure that seems to pre-date the construction of the hillfort is a platform and enclosure just to the S of the lower cashel. This may be noted here in a section of the 1840 Ordnance Survey map. (Grogan, Eoin. The North Munster Project. Vol. 1. Bray, Co. Wicklow: Wordwell, 2005. 124-25.)