What is the main draw in Dumbarton, West Dunbartonshire?

In Dumbarton, West Dunbartonshire, the main draw is Dumbarton Castle, which is dramatically perched on top of waterfront volcanic rock. History lovers will be interested in this castle, one of the oldest fortified sites in Britain. West of the town, the Overtoun Estate has wooded glens, parkland, exotic gardens and good views of the surrounding Kilpatrick Hills.