Stromboli is a small volcanic island in the Tyrrhenian Sea, just off the north coast of Sicily. Referred to by some as the "Lighthouse of the Mediterranean," Stromboli is in a constant state of mild volcanic activity, so don't venture out on a hike without an experienced guide.

Yellowstone National Park, America's first national park, stands as a stunning testament to nature’s raw power and beauty. Located primarily in Wyoming, with portions extending into Montana and Idaho, Yellowstone offers visitors a chance to witness incredible geothermal wonders, such as the famous Old Faithful geyser that faithfully erupts every 60 to 110 minutes.

Originating as a tiny fishing village in 1038, modern Kehl has become an important link between Germany and France. Rhine River cruises most often use Kehl as their gateway to the much larger and better-known Strasbourg. The savvy traveler, though, might choose to skip the jaunt across the river and enjoy many similar sights, shopping and cuisine as those offered in the teeming French city.

San Juan, Puerto Rico’s capital, is a city where cobblestone streets lead to centuries-old forts and pastel-colored buildings overlook the Atlantic. The district of Old San Juan is a UNESCO World Heritage Site, known for its Spanish colonial architecture and thick stone walls that once defended the city from pirates and naval attacks. The city hosts regular events such as La Campechada, which celebrates Puerto Rican art and literature with live performances and open-air exhibits.

From grand castles to resplendent cathedrals, Tallinn’s Old Town neighborhood, a UNESCO World Heritage Site, is the perfect place to begin exploring. Enter through Viru Väravad, or Viru Gate, the former fortress whose remaining two towers beckon you into the heart of the city.