Prairie School is a late 19th and early 20th-century architectural style, most common in the Midwestern United States. The style is usually marked by horizontal lines, flat or hipped roofs with broad overhanging eaves, windows grouped in horizontal bands, integration with the landscape, solid construction, craftsmanship, and discipline in the use of ornament. Horizontal lines were thought to evoke and relate to the wide, flat, treeless expanses of America's native prairie landscape.

The Historic Park Inn Hotel and City National Bank are two adjacent commercial buildings located in downtown Mason City, Iowa, United States which were designed in the Prairie School style by the renowned architect Frank Lloyd Wright. Completed in 1910, the Park Inn Hotel is the last remaining Frank Lloyd Wright-designed hotel in the world, of the six for which he was the architect of record. The City National Bank is one of only two remaining Frank Lloyd Wright-designed banks in the world. It was the first Frank Lloyd Wright-designed project in the state of Iowa, and today carries both major architectural and historical significance. In 1999, the Park Inn Hotel was named on the Iowa Historic Preservation Alliance's Most Endangered Properties List.