Calumet is on Goose Island - it's a bit hard to find if you aren't familiar with Chicago, and the last time I was there over a weekend it was closed Saturday and Sunday. OTOH, there is Central Photo on South Wacker - it's worth the experience to wander in there! Nothing there has changed since I lived in Chicago in 1969.
Walk around the loop - be sure to get to the Picasso sculpture at Civic Center Plaza. The Auditorium Theater and Orchestra Hall on Michigan Avenue are imposing buildings, The Michigan Avenue bridge over the Chicago River is fabulous, and if the weather is nice, that's a gorgeous place to hang out and watch the world walk by. Walk up the "million dollar mile" on North Michigan to the Water Tower (across from the Hancock Building).
If you have a rental car, drive north on Lakeshore Drive to Evanston and Winetka to the Bahia Temple. Only place like that in North America.