Niagara Cave (Visit this link)

Niagara Cave is one of the most fascinating and unique geological attractions in the Midwest. During the one-hour guided tour, visitors will witness a waterfall, nearly 60 feet high, stalactites both delicate and massive, calcite flowstone, fossils that have been dated to over 400 million years old, and a wedding chapel in which over 300 weddings have been performed, plus much more.

Niagara cave is a constant 48 degrees year around, so a light jacket or sweatshirt is suggested. Also, walking shoes are recommended.

http://www.niagaracave.com