St Aubin's Fort was developed on a rocky islet off the coast at the western end of St Aubin's Bay. It was finished in the 1540s. At that time St Aubin was the primary port on Jersey and the fort controlled the entrance. In the 17th century the Civil War the Parliamentarians turned it into a stronger fortress, by building a bulwark on it, and when the Royalists regained possession they replaced this with granite ramparts and added a storey to the tower. In the 18th century, and again in the 19th, the fort was rebuilt twice, but in peaceful Victorian times it was let as a summer residence. In the Second World War the Germans strengthened the fort with turret guns and concrete casemates.
A causeway extends from the road in front of the Royal Channel Islands Yacht Club to the fort, and one can walk out at low tide. However, the fort itself is closed to the public. Jersey's Sea Scouts use the fort as a headquarters, storing their sails and other equipment in a German bunker built into the fort. They have also converted a room in the tower into a classroom.
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.