Cairn Catto is a Neolithic long cairn near the village of Longside, Aberdeenshire, Scotland. It was designated a scheduled monument by Historic Environment Scotland on 6 July 1973.
Cairn Catto is located southeast of Longside, in Aberdeenshire, Scotland. The site is four miles north-west of Cruden Bay, to the west of the minor road between the A952 and the A950.
The cairn measures about in length and tapers in breadth towards the north-west. It is a wedge-shaped cairn aligned north-west to south-east, built of boulders of pink granite. The south-west side of the cairn has been heavily robbed. Various deep holes and quarry scoops are visible at the south-east end where stones have been removed. The Arbuthnot Museum in Peterhead houses two stone axes that were found at Cairn Catto in 1885.