Fabulous find, Slowhatch. Let's have a little more on Visegrad, such as:
One of Hungary's foremost tourist attractions and repositories of its cultural heritage, the famous Visegrad Castle. Visegrad Castle is a good half hour's hike uphill from the Danube. Its impressively large walls provide some incredible views of the surrounding river valley. The town of Visegrad is situated in a picturesque and strategic location north of Budapest at the bend of the Danube River. It was used by the Romans as a military fortress in the 4th century and became a Slavic settlement in the 9th century when they named it Visegrad, the Slavic word for "high castle." The citadel was protected by a moat carved from the rock and its Treasury Tower was where the royal insignia were stored.
Visegrad Castle is about 25 miles directly north of Budapest, but maybe 30 miles by boat.