Cook Hall was named for John Williston Cook, the fourth president of the school (1890-1899), although it was originally called the Gymnasium. Cook was instrumental in promoting physical fitness for both men and women at ISNU. The building was once known as "Altgeld’s Folly," named after Governor Peter Altgeld, who rejected the first design in favor of a German style, reminiscent of the castles along the Rhine.
The "Old Castle" as this building is often known, was designed by Miller & Fisher, local architects, and completed in 1898. Although it contains the elements favored by Altgeld, which is the Gothic turreted-style with towers and battlements, architect George Miller gave it a Richardsonian flavor by using rusticated Bedford limestone. It was designed as a fireproof building. The University decided to move the library to this new fireproof building for protection.
Cook Hall’s original use as a gymnasium featured the exercise equipment of the day—ropes, ladders, rings, slippery pole, parallel bars, turing, huge leather horses, and racks of Indian clubs and dumbbells. Plans for the inclusion of a bowling alley and a swimming pool located in the subbasement never came to fruition.
In later years, the tower housed the University radio station, WGLT, and rehearsal halls for the School of Music. It was the first building in the Town of Normal listed on the National Register of Historic Places.