Mechanic and Military Hall
The first building commissioned by the new Illinois Industrial University was the Mechanic and Military Hall, designed by John Mills Van Osdel.   Inaugurated the afternoon of September 13, 1871,  the $25,000  building reflected the University's growing investment in engineering sciences and the military service mandated by the Land Grant Act. Images of medieval castles instantly sprung to the mind when gazing upon the building, entertained by the building's fortress-like appearance with four massive turrets anchoring its corners.
The two-story brick building was 128 feet long and 88 feet wide. Its second story was entirely occupied by the enormous Drill Hall. Measuring 120 by 80 feet, the Drill Hall was "sufficient for the evolutions of a company of infantry, or a section of a battery of field artillery".  One of the towers contained an armorer's shop, along with a military model room for strategic planning, an artillery room, and a band room for the military band.
The first floor was entirely dedicated to the engineering sciences, with a boiler, steam engine, forge, tank room, and machine shop. Lathes and other word-working equipment were available in the shops, and a pattern and finishing shop, along with paint, printing, and draughting shops were also contained in the building, providing a self-contained production environment.
The building was destroyed by fire in 1899.