Coursing through 10 countries, the Danube is the second-longest river in Europe. This waterway, lined with fortresses and castles, rises in Germany's Black Forest and runs for 1,770 miles to the Black Sea. The Danube is an essential commercial thoroughfare for central and southeastern Europe, and several river cruise companies sail vessels on it year-round. Destinations along this river include Vienna, Budapest, Passau and Bratislava.

In Chile's arid Norte Grande, only one river in 700 miles of coastline makes it to the sea. Many towns have never experienced rainfall and depend on "Fogcatchers" to collect the morning dew for drinking water.

Carcassonne is a fortified city in southern France, rising above the Aude River with walls and towers that feel lifted from another century. Its origins stretch back to Roman times, but the city is best known for its medieval citadel, rebuilt and expanded during the Middle Ages when Carcassonne became a strategic stronghold on key trade and military routes.

Ascension island, British dependency of St. Helena, in the South Atlantic Ocean, about midway between Africa and South America and 700 miles northwest of St. Helena. The small, volcanic island was sighted by the Portuguese in 1501, but it was uninhabited until the exile of Napoleon to St. Helena in 1815.

Nestled along the south bank of the Danube, this historical Austrian city bursts with charm. A favorite stop on European river cruises, the city's most famous attraction is Melk Abbey, which dates back to the 11th century. The original Benedictine structure was lost to fires and foreign invasion, then rebuilt during the 18th century in lavish Baroque style, including a library and inner church covered in magnificent frescoes and gilded fixtures.