There are a number of observatories that are easily accessible to people in the Chicago area. In fact, located in the heart of downtown Chicago is the Adler Planetarium's Doane Observatory.
Just to the north in Evanston is the historic Dearborn Observatory on the grounds of Northwestern University. It has been many years since I have visited the Dearborn Observatory and do not have an article available but for more information, you can visit the Dearborn Observatory web site.
The newest observatory in the neighborhood (at least my neighborhood) is the Harper College Astronomical Observatory in Palatine Illinois which is regularly open to the public. It is worth noting that local chapters of the National Space Society, as well as the National Space Society itself, helped to raise funds for the construction of this observatory.
Need someone to talk about space to your group? Check out the Chicago Society for Space Studies Speakers Bureau
For space art, astronomy, and digital photography stories, visit the Artsnova Blog