A charming city nestled on the banks of the Rhine, Mainz, Germany lies southwest of Frankfurt and is replete with historic buildings and famous museums. The city's Altstadt district meets the river's edge and boasts a variety of beautiful and fascinating landmarks.

A lesser-known river port in the Mekong Delta, Sa Dec was once the capital of Dong Thap province of southern Vietnam. Today, it is best known for its flower gardens and authentic bustling market. The city is also famous as the setting for French writer Marguerite Duras' 1984 novel, The Lover, and its 1991 film adaptation of the same name.

The capital and largest city in Hungary, Budapest is a favorite European destination for millions of tourists each year. Once the center of the Austro-Hungarian Empire, this cosmopolitan city and UNESCO World Heritage site has plenty of historical and cultural landmarks to explore.

Seven miles outside of historic Athens, the Greek coastal city of Piraeus lies upon the sparkling waters of the Aegean Sea and is the largest passenger port in Europe, servicing nearly 20 million passengers per year.

Ho Chi Minh City, formerly known as Saigon, is the most populous city in Vietnam at 9 million people. It is an enticing mix of the old and new, with European architecture due to French colonization to towering skyscrapers and modern shopping malls.