An axial stone circle is a megalithic ring of stones of a particular design found in County Cork and County Kerry in southwest Ireland. Archaeologists have found it convenient to consider the axial five-stone circle and axial multiple-stone circle separately. The circle has an approximate axis of symmetry aligned in a generally northeast–southwest direction. The stone at the southwest side of the circle, rather than being an upright orthostat like all the rest, is a slab lying horizontally with its long thin edge along the circumference of the ring. Because it marks the axis of the circle it is called the axial stone.
Constructed in the Bronze Age, axial stone circles have an odd number of stones with two stones placed on either side of where the axis crosses the northeast side of the ring. The pair of uprights is generally taller that any of the others and they frame what is sometimes regarded as the entrance, or portal, to the ring. For this reason these two stones are called portal stones.
Early in the 20th century this type of circle was called a recumbent stone circle by analogy with similar examples in Scotland but when it became clear there were substantial differences the term Cork–Kerry stone circle was adopted and later the term "axial stone circle" became used as a synonym. Ó Nualláin (1984) has published a comprehensive survey.
Drombeg stone circle has been excavated and has been particularly well studied. When an observer looks southwest along its axis the midwinter sun can be seen to set behind a notch on the skyline directly over the axial stone. However, no other axial circles have a comparable characteristic and statistical analysis over the circles as a whole show their alignments do not point accurately to any significant rising or setting positions of sun, moon or major stars.