St. Louis (Alton), Missouri, United States

Embark your ship and settle into your stateroom. Alton is the gateway to St. Louis, which was a passageway into the Louisiana Territory during the 19th century. In 1904, St. Louis gained recognition as host of a world’s fair (officially called the Louisiana Purchase Exposition), whereby some accounts the ice-cream cone was introduced. Today, it is home to rich architectural treasures—among them, the Cathedral Basilica of St. Louis, with its 41-million-piece mosaic; the Renaissance Revival City Hall; the 19th-century Old Courthouse; and the Gateway Arch, standing along the Mississippi as a monument to westward expansion.