Research facility on U of M's north campus contains the Michigan Historical Collections, as well as U of M's archives. Mon-Fri, 9am-5pm. Sat , 9:00am-3:00pm. The Detroit Observatory, the first observatory built in the state of Michigan, is also part of the Bentley Historical Library. It is open for tours on select Sundays and for viewing nights throughout the year. Visit web page for more information.