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.

This small yet charming city in Alaska's panhandle is a throwback to the gold rush era. Skagway is a well-preserved part of Klondike Gold Rush National Historical Park.

Kalmar Union, combination of the crowns of Denmark, Sweden, and Norway, effected at Kalmar, Sweden, by Margaret I in 1397. Because all three crowns were elective, the union could not be maintained by inheritance. Margaret's successors controlled Sweden intermittently until Gustavus I of Sweden dissolved the union (1523). Norway became independent in 1814.

Carroll is a small town in northern New Hampshire within the White Mountains region, known for its forested slopes, mountain views, and proximity to several major outdoor attractions. The town includes the village of Twin Mountain, which sits near the junction of several roads crossing the northern White Mountains. Its landscape is shaped by the Ammonoosuc River and surrounding peaks, including Mount Washington farther east.

Nestled in the Andaman Sea, Langkawi is an idyllic island escape renowned for its pristine beaches, lush landscapes, and vibrant culture. This Malaysian archipelago, comprising over 100 islands, boasts a range of natural wonders, including the Langkawi Sky Bridge, an architectural marvel suspended 700 meters above ground.