The famous Edinburgh Castle is an essential visit for anyone with an interest in the remarkable history of Scotland.
Large, very old castle perched high on a hill. Also included city tour.
Provider: Princess Cruises
The city tour was interesting, but the portion at Edinburgh Castle was completely rushed with little time to explore. I'd suggest going on your own to the castle.
Provider: Azamara Club Cruises
Not only is this a fascinating castle, but it has museums in it detailing Scottish military history, the royal jewels, etc. We heard the cannon go off at 1 PM and were taken around by a guide who explained it all to us (free).
A good time was had by all.
Provider: Independent Operator