Cleits are small stone sheds with a roof of a large flat stone covered with earth and turf. The walls are built of stones with little gaps between them. This means that the wind can whistle through and help things kept inside them dry and cool. In a windy place like St Kilda it's a perfect design!
They were used by the St Kildan people to store dead seabirds (for eating), eggs and feathers, crops and peat and turf (which were used as fuel). There are 1,260 of them all over the main island of Hirta.

Today cleits make ideal homes for many birds, including Storm and Leachs petrels, which have a very unusual call.