A crannog, which is an artificial or partially artificial island constructed from layers of timber, peat, stone, and brushwood, represents one of the most enduring forms of settlement in the Irish landscape. People built and inhabited them from the Bronze Age well into the early medieval period, choosing the water not for convenience but for the security it offered, a natural moat requiring no walls.

Crannogs are found throughout Ireland and Scotland, and Galway has a number of recorded examples. They tend to surface in the historical record only gradually, sometimes spotted as an unusual rise in a lake, or revealed when water levels drop in a dry summer. The Derrycallan example is recorded as a monument, placing it among a class of sites recognised for their archaeological significance, though the particular history of this individual crannog, its dates of construction or occupation, and any finds associated with it, remain to be brought fully into the public record.