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 Gravensteen is a castle in Ghent originating from the Middle Ages. The name means 'castle of the counts' in Dutch. Arnulf I (918–965), Count of Flanders, was the first to fortify this place, building a medieval bastion on this high sand dune, naturally protected by the river Leie and its marshy banks. This bastion consisted of a central wooden building and several surrounding buildings, also in wood.
In the early 11th century, the wooden building was replaced by a stone residence, consisting of three large halls that made up three storeys, connected by a stone stairwell. The monumental stone staircase, the light openings, the fireplaces built into the walls and the latrines were signs of considerable luxury and comfort in those days. There was probably also a tower.