The Natural History Building on the main Quad houses one of the best natural history collections in the American Midwest. The public museum section includes impressive mounted skeletons and taxidermy — the star exhibit is a full-sized mounted mastodon skeleton excavated from Illinois, surrounded by other Pleistocene megafauna. The entomology collection is one of the largest in North America, though most of it is held in research storage rather than on public display.
Admission is free, and the building itself — designed in the same Gothic limestone style as the rest of the Quad — is worth visiting as architecture as well as museum. The second-floor gallery with its dark wood cases and 19th-century display philosophy has not been modernised, which is either a flaw or a charm depending on your temperament.