The arch, which is as tall as a 63-story building, represents the historic “gateway” to the western half of the United States. The 630-foot-tall Gateway Arch, the tallest monument in the United States, is without a doubt the most famous attraction in the city of St. Louis attractions for any river cruise visitor. Gateway Arch National Park is the home of two major St. One in particular stands out in a big way. The city is big enough to offer any visitor a wide variety of attractions. It also is a common port of call for cruises that begin on the Ohio River and merge with the Mississippi. Paul and Minneapolis as well as the southernmost point at New Orleans. This major midwestern city is about midway between the northernmost point on the Mississippi at St. Louis is in an ideal location for almost any cruise along the Mississippi and Ohio rivers.