Azerbaijan, often called the “Land of Fire,” sits at the crossroads of Europe and Asia along the Caspian Sea. Its capital, Baku, blends futuristic architecture with centuries-old history.

In the southern deserts of Peru, Nazca invites visitors to look beyond the horizon. This small city is world-famous for the mysterious Nazca Lines, enormous geoglyphs etched into the desert floor more than 1,500 years ago. From the air, shapes like hummingbirds, monkeys, and even a stylized astronaut come into view, some stretching over 300 meters. Their exact purpose remains a mystery, fueling decades of theories.

Turkmenistan is a land of striking contrasts, where vast deserts meet ancient Silk Road history. The country is dominated by the Karakum Desert, an expanse of sand and scrub that covers most of its territory, yet it is also home to oases where cities flourished as trading posts for caravans journeying between Persia, China, and beyond.

One of the major rivers of the Iberian Peninsula, the Douro in north-central Spain and Portugal just might be the world's most beautiful wine region. Most of the river on the Spanish side isn't navigable, so river cruises generally travel roundtrip from Porto, on the coast of the Atlantic.

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.