What makes this particular site curious is not the rath itself, which is a reasonably common form in the Irish landscape, but the rectangular feature pressed against its north-western edge. That combination is less expected.

A rath is a ringfort, a type of enclosed farmstead built during the early medieval period, roughly between the fifth and twelfth centuries. They were typically defined by one or more earthen banks and served as the homesteads of farming families, providing enclosure for livestock and a degree of social status for their occupants. The Ballybroder example measures approximately 35 metres in diameter, placing it at a modest scale. What distinguishes it is the rectangular annexe abutting the monument to the north-west, measuring roughly 26 metres on its longer axis and 23 metres on the other, and also defined by a bank. Rectangular annexes attached to circular raths are known elsewhere in Ireland but are far from universal; they may have served as enclosures for animals, gardens, or subsidiary structures. Whether this one was built at the same time as the rath or added later is not established, and the relationship between the two features is recorded as possible rather than certain.