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.

Nestled along the south bank of the Danube, this historical Austrian city bursts with charm. A favorite stop on European river cruises, the city's most famous attraction is Melk Abbey, which dates back to the 11th century. The original Benedictine structure was lost to fires and foreign invasion, then rebuilt during the 18th century in lavish Baroque style, including a library and inner church covered in magnificent frescoes and gilded fixtures.

There's more than meets the eye in Savona, a Northwest Italy port city many cruise ship passengers are lucky enough to find themselves in. The giant Fortezza del Priamàr looms over the water, providing a unique welcome. Be sure to stroll through the city's genteel, impressive medieval center, visit the beautiful Savona Cathedral and see marvelous artistic works from centuries past at the Ceramics Museum.

Pamukkale is a fairyland of dazzling white, petrified castles. It is a magical and spectacular natural site, unique in the world. Thermal spring waters laden with calcareous salts running off the plateau's edge, have created this fantastic formation of stalactites, cataracts and basins.

Palenque, nestled in the lush jungles of Chiapas, Mexico, offers an enthralling glimpse into the grandeur of the ancient Maya civilization. The city is renowned for its well-preserved ruins, which include the majestic Temple of the Inscriptions, where the tomb of the ruler Pakal the Great was discovered in 1952.