CHICAGO (AP) — Chicago’s Peggy Notebaert Nature Museum is celebrating its 15th anniversary by offering free admission on Sundays during October.

The museum opened its doors in Chicago’s Lincoln Park in 1999. It’s operated by the Chicago Academy of Sciences, and was intended to fill a void for people in Chicago who had lost their connection to nature.

The museum has a butterfly haven that’s home to more than 1,000 butterflies of 75 different species. Specimens in the museum’s collection include nearly 14,000 birds and 15,500 plants.

The museum also offers classes and field trips.

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