The castle stood until 1648, when Oliver Cromwell's troops had it destroyed, taking much of the stonework to Ayr to build the citadel at Montgomerieston.The ruins of Cromwell's Fort still stand, but are overgrown and in a dangerous condition.
Exports of coal and pig iron to Europe and North America were the main trade from the town's port, which became a centre for shipbuilding.Fishing vessels and small cargo boats were the mainstay of the shipyard until the 1950s, when the yard ceased to exist as a result of foreign competition.A smaller yard, Mc Crindle's, operated until the 1980s before it ceased trading.Situated on the north side of Irvine Bay, an inlet of the Firth of Clyde, Ardrossan lies 5 miles (8 km) northwest of Irvine.One of the Three Towns of North Ayrshire, along with Saltcoats and Stevenston, Ardrossan was founded as a resort in 1805 by the Earl of Eglinton, its deep-water harbour was suitable for steam boats connecting with Arran, Belfast, the Isle of Man and Campbeltown.
Ardrossan also became a seaport for the export of coal, iron and chemicals, although it never realised its ambition to be a terminus on the proposed Glasgow, Paisley and Ardrossan Canal.Created a burgh in 1846, one of the last to be established in Scotland, Ardrossan became a centre of railway engineering, shipbuilding and oil refining. It still maintains a ferry link with Arran (dating from 1834) and the Isle of Man (dating from 1892), and timber bound for the paper mill at Irvine is imported. Ardrossan's roots can be traced to the construction of its castle 'Cannon Hill', thought to be in around 1140, by Simon de Morville.The castle and estate passed to the Barclay family (also known as Craig) and through successive heirs until the 14th century when it passed to the Eglinton family on the death of Godfrey Barclay de Ardrossan, who died without an heir.Sir Fergus Barclay, Baron of Ardrossan was said to be in league with the Devil and in one of his dealings, set the task for the Devil to make ropes from sand; on failing to do so, the Devil kicked the castle with his hoof in frustration and left a petrosomatoglyph hoofprint.