Decorah Ice Cave State Preserve in northern Decorah, Iowa, protects a small cave site on three acres at the edge of Barbara Barnhart VanPeenen Memorial Park. Though modest in size, it includes one of the Midwest’s largest ice caves and a well-known feature of the Driftless Area’s karst landscape. Its most distinctive characteristic is that ice forms seasonally, beginning near the entrance in January or February, spreading downward, and often lasting into late August. Given to the city in 1954, the site became a state geological preserve in 1973 and joined the National Register of Historic Places in 1978. Safety concerns later limited interior access.