Greenan Castle is a 16th-century ruined tower house, around 4 kilometres southwest of Ayr. Situated at the top of a sea cliff, it was originally a promontory fort converted into a motte-and-bailey in the 12th century. In the 15th century a tower house was built by the Lords of the Isles, which later passed into the hands of the Kennedy family.
The first known defensive structure on the site was a promontory fort, probably a fortified farmstead. Four concentric curved ditches, each around 3 metres wide, cut off the headland with the exception of a single causeway to provide access. It is not known how long this settlement was occupied, but the site was re-used in the twelfth century.
Beside the tower are traces of a walled courtyard and outbuildings, probably stables and a kitchen block, as the small tower has no kitchen within its walls.
The castle passed through various members of the clan before ending up in the hands of Thomas Kennedy, Earl of Cassillis in 1766. Around this time the residential use of the castle seems to have stopped; today the structure is a ruin.
References:The Broch of Clickimin is a large and well preserved, though somewhat restored broch near Lerwick. Originally built on an island in Clickimin Loch (now increased in size by silting and drainage), it was approached by a stone causeway. The water-level in the loch was reduced in 1874, leaving the broch high and dry. The broch is situated within a walled enclosure and, unusually for brochs, features a large 'blockhouse' between the opening in the enclosure and the broch itself. Another unusual feature is a stone slab featuring sculptured footprints, located in the causeway which approached the site. Situated across the loch is the Clickimin Leisure Centre.