The Corn Palace is located in Mitchell, SouthDakota: http://www.cornpalace.org/
Although, to be fair, the original Corn Palace was in Sioux City, Iowa, built in 1887. They built a new one every year, for about 4 years, until a bad harvest forced them to stop the practice in 1891. The first CornPalace in Mitchell was built in 1892.
Descriptions:
Every year, they start from scratch and put a new mural, made entirely of different grains, on the outside of the Corn Palace. As you can imagine, the risk of fire is great, so the local fire department made a rule that no flammable material is allowed on the bottom 10 feet of the palace. It's just plain old brick... -- SeanOleary