This 73,000-square-foot museum focuses on the biodiversity of the Midwest. One of the most popular exhibits is the Judy Istock Butterfly Haven, featuring more than 1,000 winged beauties in a tropical setting. M-F 9 am-5 pm, Sa-Su 10 am-5 pm. Admission $9; students and seniors $7; children $6. Suggested donation days on Th for Illinois residents.