The solemn exterior conceals an opulent interior of this 17th century church.

An exquisite Baroque church in Vienna's old town.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

The beautiful baroque library of the Hapsburg empire.

Two nations form a rare four-sided border at the peak of a mountain, philosophical questions result.

The world's most important buildings shrunk to a tiny size.

Archduke Ferdinand II's collection of rare objects is considered one of the oldest museums in the world.

This spire on an Austrian mountain is wrapped around a long spiral slide and has the world's tallest wooden observation deck.

The medieval network of canals hidden underneath the city is opened to explorers each year.

The shell of a medieval fortress offers commanding views of the area it once protected.

This series of underground chambers contains Europe's largest subterranean lake that is slowly drained each day.

Visitors dip into a variety of pools of what was once ice.

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

A centuries old castle atop a dormant volcano houses museums devoted to both women and witches.

Each year melting snow turns these Austrian hiking trails into scuba zones.