Dundonald Castle is situated on a hill overlooking the village of Dundonald, between Kilmarnock and Troon in South Ayrshire, Scotland. Dundonald Castle is a fortified tower house built for Robert II on his accession to the throne of Scotland in 1371 and it was used as a royal residence by Robert II and his son Robert III.
The present castle stands on land where evidence suggest there used to be a hill fort. It is thought that a mixture of large timber built round houses and straight-sided structures occupy the interior. A timber laced stone rampart defines and defends the hill fort. The timber lacing caught fire and burnt with such intensity that the surrounding stonework melted, or vitrified. This firing happened about 1000 AD and seems to mark the end of the hill-fort’s existence.
It was about this date that the British Kingdom of Strathclyde ceased to exist, being absorbed into the Kingdom of Scotland.
The place name Dundonald means "fort of Donald". It appears to be derived from the British *Din Dyfnwal (the British personal name Dyfnwal is cognate to the Scottish Gaelic Dòmhnall and English Donald). The eponym of the fortress is unknown, although he may have been any of the numerous kings of Alt Clut/Strathclyde who bore the name Dyfnwal from the eighth century to the tenth century.
There have been three medieval castles present on this site. The first was built by one of the stewards of the king of Scots, most probably Walter, the first steward, who came to Scotland in 1136. There is no surviving evidence of this castle above ground today.