Pennsylvania offers more than just a glimpse into American history, it invites travelers to walk through it. In Philadelphia, the Liberty Bell still draws visitors from around the world, while Independence Hall, a UNESCO World Heritage Site, is where both the Declaration of Independence and the U.S. Constitution were debated and signed. Just a short walk away, modern museums like the National Constitution Center offer hands-on exhibits that connect the past to today’s civic questions.

If you find yourself in Rotterdam, there's a strong chance you've arrived by water. This popular port city (the second largest in the Netherlands) has gone through an architectural renaissance since World War II, with daring, innovative structures dotting the city (cube houses!) and defining its skyline. Café culture is on the rise here, so grab yourself a table and a cup.

ABERDEEN -- Scotland's third-largest city (pop. 187,000) is characterized by buildings of beautiful white granite. Set beside the North Sea, Aberdeen is both a university town and the capital of the Scottish oil boom. It is also one of Scotland's largest seaside resorts (though its appeal is confined to those who like their water well-chilled).

Libya, located in North Africa along the Mediterranean coast, is a country of vast deserts, ancient history, and dramatic landscapes. Much of its terrain is dominated by the Sahara Desert, with sand dunes, rocky plateaus, and oases shaping life across the country.

Tongatapu, the main island of Tonga, is where tradition, history, and the South Pacific’s natural world intersect in quiet and unexpected ways. As the political and cultural center of the Kingdom of Tonga, it is home to the capital city, Nukuʻalofa, as well as ancient royal burial grounds, dramatic coastal blowholes, and friendly villages where daily life unfolds slowly.