Built in 1854, it has its original instruments intact. It's on Observatory Street. The Detroit Observatory is open for public tours, usually twice a month. Special guided group tours may be arranged. The dome was repaired in 2009 for the International Year of Astronomy, and fall of 2010 saw the first series of public viewing nights in several decades.
website: Detroit Observatory
Viewing Nights: Viewing Nights
historical photos: http://www.whatwasthere.com/browse.aspx#/ll/42.2708716,-83.7263294/
- Wikipedia: Detroit Observatory