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.

Stretching 277 miles in length and more than a mile deep, this vast canyon reveals layers of geologic time stacked like pages in a book. Standing on the South Rim, visitors can look out over colorful cliffs and winding trails that have drawn explorers, artists, and travelers for generations. The views change with the light starting with crimson at sunrise, golden at sunset, and every hue in between.

St. Lucia is an island of verdant landscapes in every direction: A dense rain forest rises up and covers The Pitons' twin peaks, and in the valleys, the sun's rays dance upon the large yellow-green leaves of banana plants. Beyond all the greenery, you'll find isolated coves, stunning beaches, colonial towns, quiet fishing villages and first-class yachting facilities.

Salalah stands out with its rare blend of desert and tropical appeal. Unlike much of the Arabian Peninsula, this coastal city is transformed by the seasonal Khareef (monsoon), turning the landscape lush and green between June and September.

Often called the Eternal City, Rome stands alone as Italy's most visited destination. The third most populated city in the European Union, Rome boasts ancient sites, yet has a modern flair — an exhilarating mix of the Old World and the new.