Alexis B.
Yelp
My friend and I spent a few days driving around Lower Austria and Burgenland at the beginning of this month. We stopped in Aggstein to see the ruins of Aggstein Castle, which was well worth our time!
The castle was built in the 12th century but after years of neglect beginning in the 17th century, fell to ruins. The ruins sit atop a hill above the Danube River, and there are some incredible views.
The castle has a small restaurant (they had inside seating, which wasn't open when we visited, but they had plenty of outdoor seating, which was lovely), where we enjoyed lunch when we arrived at the castle. We had some frankfurters with rolls, horseradish, and mustard - super simple and delicious. They also serve lemonade, beer, and other food. It was packed when we ate lunch, because a school group was visiting (lots of orders of French fries), but the food was fast, and it couldn't have been more convenient. 
But the reason to visit is definitely, easily the experience of walking through the structure of the ruins. It's really very cool to explore and take photographs of the structure - and the wonderful views you can see though the window and doorframes of the ruins. 
There wasn't much in the way of signage that I could see, but it's interesting to walk around and you can Google the castle before you walk around to get some context for your visit. A great stop in Lower Austria (we visited between stops at Melk and wineries in the Wachua Valley)!