4 Best Sights in Vienna Woods, Lake Neusiedler, and the Danube River, Austria

Just across the Nibelungen Bridge from the Hauptplatz, this highly acclaimed "Museum of the Future," opened in 2009, pays tribute to the confluence of art, technology, and society. Permanent features at the museum include the 3-D cinema room, which allows you to fly over Renaissance cathedrals or explore ancient civilizations, as well as exhibits on the latest developments in robotics and the origins of the universe—all with English explanations. As well as its permanent exhibits, the center also hosts annual festivals, with a different theme each year. Allow at least half a day to experience all the cybersites here. When you need a break, visit the Cubus Café Restaurant Bar on the third floor for refreshments and a spectacular view overlooking the Danube and Lentos Kunstmuseum opposite.

The remains of the important Roman legionary fortress and civil town of Carnuntum, which once numbered 55,000 inhabitants, extend about five kilometers (three miles) along the Danube from the tiny village of Petronell to the next town of Bad Deutsch-Altenburg. The recent discovery here of an ancient school of gladiators delighted archaeologists and significantly raised Carnuntum's stature, and rightfully so. Visitors can tour the grounds, which include two amphitheaters (the first one seating 8,000) and the foundations of former residences, reconstructed baths, and trading centers—some with mosaic floors. The ruins are quite spread out, with the impressive remains of a Roman arch, the Heidentor (Pagans' Gate), a 15-minute pleasant walk from the main excavations in Petronell. You can experience what Roman life was like circa AD 380 in the elegantly furnished Villa Urbana. Many of the excavated finds are housed at the Museum Carnuntinum at Bad Deutsch-Altenburg. The star of the collection is a carving of Mithras killing a bull. Guided tours in English are available in July and August at noon; otherwise they are in German only.

When you want to escape the hustle and bustle of Linz, just hop on the electric railway Pöstlingbergbahn for a scenic ride up to the famous mountain belvedere, the Pöstlingberg. The narrow-gauge marvel has been making the journey since 1898, and today the line extends to Hauptplatz. Europe's steepest non-cog mountain railway gains 750 feet in elevation in a journey of roughly four kilometers (2½ miles) in just 20 minutes, with neither pulleys nor cables to prevent it from slipping. Halfway up is the Linz Zoological Garden and a children's petting zoo, but it's at the top where you'll enjoy the best views, with the city and the wide sweep of the Danube filling the foreground and the snowcapped Alps on the horizon. Also here is the Church of the Seven Sorrows of the Virgin (Sieben Schmerzen Mariens), an immense and opulent twin-towered Baroque pilgrimage church (1748) visible for miles around. Kids will enjoy the Grottenbahn, or Dragon Express, where they're whisked through a world of dwarves, forest creatures, and other fairy-tale folk, while adults can drink in the views—along with a glass of chilled white wine—from the terrace of the Pöstlingberg Schlössl restaurant.

A true Baroque gem, this castle is shining even more brilliantly since the completion of extensive restorations. The product of that master designer and architect Johann Lukas von Hildebrandt, who in 1732 reconstructed the square castle into an elegant U-shape building, the Schloss opens up on the eastern side to a marvelous Baroque formal garden that gives way toward the river. The famed landscape painter Bernardo Bellotto, noted for his Canaletto-like vistas of scenic landmarks, captured the view before the reconstruction. His three paintings were used as a guide for restoring the gardens to their Baroque appearance.

The castle was once owned by Empress Maria Theresa, mother of Marie Antoinette. You can visit the suite the empress used during her royal visits, faithfully re-created down to the tiniest details, as well as the two-story chapel in which she prayed.

In 2016, the Schlosshof added some highly popular adventure paths to the interactive visitor experience. Children can play the roles of stable boys and maidens, performing various chores and encountering blacksmiths, falconers, or bakers along the path. You might stumble upon a large estate farm that is home to horses, goats, donkeys, and several other animals. The complex also includes a restaurant and pâtisserie, both with indoor and outdoor seating. Guided tours and audio tours of the castle and garden are available in English, but it's also possible to wander around the buildings and grounds on your own. The castle is about eight kilometers (five miles) south of Marchegg. Be sure to enjoy the panaromic view (you can even see across the border into Slovakia and it's capital Bratislava from here). If you come in winter, you can enjoy the charming Adventmarkt set up on the sprawling grounds.