L'Islet is a complicated and unique variation of a Cist-in-Circle monument. It dates from the Chalcolithic (2500 - 1800 BC). A central capstoned cist with an antechamber is surrounded by a D shaped ring of stones. Attached to the outer ring are four smaller rings two of which contain further slab lined cists. No bones were found but the central chamber contained a biconical pot. It is probable that the outer cists were later additions to an earlier single Cist-in-Circle.
References:Doune Castle was originally built in the thirteenth century, then probably damaged in the Scottish Wars of Independence, before being rebuilt in its present form in the late 14th century by Robert Stewart, Duke of Albany (c. 1340–1420), the son of King Robert II of Scots, and Regent of Scotland from 1388 until his death. Duke Robert"s stronghold has survived relatively unchanged and complete, and the whole castle was traditionally thought of as the result of a single period of construction at this time. The castle passed to the crown in 1425, when Albany"s son was executed, and was used as a royal hunting lodge and dower house.
In the later 16th century, Doune became the property of the Earls of Moray. The castle saw military action during the Wars of the Three Kingdoms and Glencairn"s rising in the mid-17th century, and during the Jacobite risings of the late 17th century and 18th century.