A Sporting Tour Through the Northern Parts of England, and Great Part of the Highlands of Scotland (1804)
Dumbarton Castle, nestle in the basalt of Dumbarton Rock by the River Clyde, is purported to be the longest recorded history of any stronghold in Scotland. Archaeological evidence suggests settlement patterns from at least the Iron Age. The Castle dates from the early Medieval period, and Merlin is reported to have some connection to Dunbarton.
The castle and rock have a long and storied history, involved in battles, imprisonments, and various political machinations. By the Regency era, it was a notable site for travellers.
Says one account:
Observations on a Tour Through the Highlands and Part of the Western Isles of Scotland (1800)
Near Loch Lochmond, there were many scenic attractions to the traveler desirious of taking in the wonders of Scotland and the mountains.
The New Monthly Magazine and Universal Register Volume 14 (1820)
Here is an account of what would greet the Regency visitor:
The Pocket Magazine of Classics and Polite Literature Volume 2 (1818)