Located in Chicago, Illinois, the Willis Tower--formerly known as the Sears Tower--is the fifth-largest steel structure in the world. Visitors to its observation deck can view four states. The Willis Tower has the highest number of occupied floors, highest elevator ride and the highest roof deck in the world.
Completed in 1883, the Brooklyn Bridge in New York City connects Manhattan and Brooklyn. The oldest suspension bridge in history, the steel structure crosses the East River for 5,989 feet. It was named a National Historic Landmark in 1964.
The Gateway Arch in St. Louis, Missouri, is a stainless steel structure that stands 630 feet high to the east of the Mississippi River. Constructed in 1947, the proper name for the arch is the Jefferson National Expansion Memorial Gateway Arch. Inside of the arch are trains that take tourists all the way up to the highest point where observation windows allow distant views of Illinois and Missouri, as well as the area directly below the arch.
Located in New York City, the Seagram Building is the home of the Four Seasons restaurant. Opened in 1958, the Seagram Building is 515 feet high with 38 floors. It is considered a work of engineering genius designed by Ludwig Mies van der Rohe in association with Phillip Johnson.