This evening, I am focusing on Dumbarton Castle which is located on the Firth of Clyde in S.W. Scotland. This site has a very long history as power base and fortification, possibly dating back about 1600 years when it was the capital of the Kingdom of Strathclyde, a Brythonic (Welsh) speaking kingdom covering southern Scotland and northern England. In fact Dumbarton Castle has the longest recorded history as a fortification. The name Dumbarton is derived from the Gaelic dun breatainn which means ‘Fort of the Britons’.