Dumbarton Castle is enthroned on the 73m high Dumbarton Rock. In its more than 1500-year history it was the scene of many feuds and skirmishes. Of great strategic importance in the Middle Ages, it always remained a suitable vantage point and place of refuge. David II hid here successfully in 1333-34 and Mary Queen of Scots in 1548 before they could flee to safer climes.
The oldest recorded stronghold in Scotland. It sits on a massive lump of volcanic rock, so you can imagine it would be hard to conquer! May be closed so check ahead if you're visiting.
Below the castle (with limited opening hours) there is the Castle Park, which is open all day and offers beautiful views of the castle. There is also the bowling club with a clubhouse and outdoor area. Here too, it seems that it is permitted to spend the night in a camper van in the car park. The large shops (including Morrisons and Lidl, with many snack bars nearby) are only about a kilometer away on foot, and the city center is similarly close (directly behind them).