For many centuries Bohemia and Austria had been united not only by the Habsburg emperors but also by trade, traffic and by social connections. Lots of citiies, villages and castles have been beautifully restored and you can be visited easily coming from Austria.
For centuries Budweis was the terminal for the salt-trade between Austria and Bohemia. In the 19th century they built the first railway of the continent from Gmunden - Linz -to Budweis, powered by horses.
The city of Budweis is wolrd known thanks to the excellent beer. Within the old city walls you find a medieval citiycentre with a large, beautiful square.
This world heritage town nestles against the river Moldau and is crowned by a beautiful castle with the famous "Mantelbrücke" that connects the older and newer parts of the castle. The old houses and narrow lanes make you feel like hiking in the Middle Ages.
Along the MOLDAU you pass
Castle Rosenberg and Abbey Hohenfurt (Visibrod)
Further suggestions for excursions:
The "Böhmerwald" and cities like Trebon,. Tabor and Telc with beautiful castles.