Dumbarton ( Dùn Bhreatainn Gaelic ) is a town in Scotland with 20,550 inhabitants ( 2001). The city is situated on the Firth of Clyde, at the mouth of the River Leven.

On the volcanic basalt rock Dumbarton rock is Dumbarton Castle, said to be the oldest castle in Scotland. Dumbarton was from the 5th century the capital of the early medieval Kingdom of Strathclyde, then capital of the traditional county of Dunbartonshire. Today it is the capital of the prefecture of West Dunbartonshire. From the 18th century until about 1960 Dumbarton was a center of shipbuilding.

Dumbarton is the birthplace of the painter George Harcourt and William Strang, the singer David Byrne and the Formula 1 racing driver Jackie Stewart.

Residential high-rises on the banks of the Leven

View of Dumbarton on the Clyde, right in the background next to the Dumbarton Rock is Ben Lomond.