One of the major rivers of the Iberian Peninsula, the Douro in north-central Spain and Portugal just might be the world's most beautiful wine region. Most of the river on the Spanish side isn't navigable, so river cruises generally travel roundtrip from Porto, on the coast of the Atlantic.

Northwest of Grand Rapids, it has a natural safe harbor off Lake Michigan

Lake Ohrid, a natural tectonic lake in the south-west corner of Macedonia, is the oldest lake in Europe and one of the oldest lakes in the world. Formed tectonically between four and ten million years ago, the lake is situated in limestone bedrock. Nestled amid mountains at an altitude of 2290 feet, the lake offers striking vistas of the surrounding beach and hills.

Viscri is a small village in Brașov County, Transylvania that feels like a place untouched by time, where centuries-old traditions remain alive in everyday life. Best known for its Saxon fortified church, the church of Viscri is one of the oldest and most impressive buildings in Transylvania, built of white-green limestone and strengthened with two rings of defensive walls added over the 16th and 18th centuries.

This cultural capital and university city holds more than 2,000 years of history and is the cultural hub of Germany. Marvel at the gorgeous twin-spired Cologne Cathedral, known for its gilded medieval reliquary and sweeping river views, or lose yourself in one of Colonge's many museums for a few hours. Cologne boasts of having most pubs per person in Germany, so make sure you sit down for a refreshing regional Kölsch beer during your travels!