Peggy Notebaert Nature Museum celebrating 166 years

CHICAGO (CBS)-- One of the oldest museums in Chicago is celebrating its 166th birthday this year.

To celebrate, the Peggy Notebaert Nature Museum is giving visitors a behind-the-scenes look at nearly 400,000 specimens.

On Thursday, the public can get a look at preserved birds, mammals, plants, fossils and more. Some are more than 200 years old. Visitors will be able to talk with the collections team as they get an up close view of the specimens.

Admission is free for Illinois residents.