Portincross Castle appears to have been built in the 14th century, with later modifications. It has been ruinous since it was unroofed in 1739, but its massive walls are still entire. It consists of an oblong keep, three storeys and a garret high, with a wing, one storey higher, placed at one end. The whole of the ground floor is vaulted and there are entrances on the ground and first floors. Macgibbon and Ross state that there has been a wall with a gateway between the castle and the edge of the rock on which it stands. This was the fortalice of the barony of Ardneil, which belonged to the Rosses, and was given by Bruce to Sir Robert Boyd of Kilmarnock. Several royal charters are signed from here, possibly used as a crossing-point to Bute. D MacGibbon and T Ross 1889; N Tranter 1965
The castle will be open daily for the first two weeks in April and at weekends and public holidays during the rest of April, and during May, June and September. We will be open every day throughout July and August.