If you want to see some photos of the castle, including the Georgian part which I took back in 2018 on a blue sky day have a look here.
There are plenty of information boards to read if you visit Dumbarton Castle. If you want to read them more easily click on the photos.
The photo below was taken from inside the guard room which has only fairly recently been opened to the public.
Dumbarton Castle has had famous prisoners over the years, including William Wallace and Mary, Queen of Scots. I believe that it was one of the many places that she managed to escape from. In fact she escaped from so many places that I suspect that it was a bit of a cat and mouse game which was being played on her.