Sintra, located just 40 minutes from Lisbon, feels like a world apart. Tucked into the hills of the Serra de Sintra, this town has drawn kings, poets, and explorers for centuries. It was once the summer retreat of Portuguese royalty, who left behind palaces and gardens that seem pulled from a storybook. The most famous, Palácio da Pena, is perched high above the town with bold red and yellow towers that blend Romanticism with Moorish and Gothic styles.

In the walled city of Siena we stand firmly planted in the Middle Ages. Siena preserved its original character more markedly than any other city in Italy.

Ol Doinyo Lengai, often called the "Mountain of God," is an active volcano located in northern Tanzania and is a must-visit for adventurous travelers. Towering over the Great Rift Valley, this majestic peak is unique due to its lava composition. Unlike most volcanoes that produce molten lava, Ol Doinyo Lengai emits natrocarbonatite lava, which is unusually cool and flows like water. This rare phenomenon makes it one of the most intriguing volcanic landscapes on Earth.

This 2,000-year-old city, where the Teutonic Order founded one of its first commanderies in the 13th century, lies on the convergence of the Moselle and Rhine Rivers. Hop on a cable car, one of the city's most popular attractions, for stunning city-wide views, or cruise down the Rhine to spot some of Koblenz's magnificent fortresses and castles, including the Ehrenbreitstein Fortress and Schloss Stolzenfels.

Durango, located in north-central Mexico, is a destination rich in history, dramatic landscapes, and cultural traditions that date back centuries. Once a key outpost during Spanish colonization, Durango played an important role in the development of northern Mexico. The city of Victoria de Durango, the state capital, features cobblestone streets and more than 1,000 officially registered historical structures.