The Chicago Symphony Orchestra is easily one of the best orchestras in the whole world. Add to that, the history of the orchestra and it's legendary brass power, this orchestra is truly something you want to see if you ever visit Chicago.
I'm lucky enough that I live only several miles away from downtown Chicago that I try to visit at least four times a year, although I'm probably going at least every two months now.
The orchestra plays almost every week during its performing season, which is from the end of September/beginning of October until June. The orchestra has many guest performances, including some of the best classical performers joining the orchestra on many different songs.
The concert hall is an old hall, but there are a wide variety of seats, ranging from floor to gallery to box. You should purchase your tickets ahead of time to ensure that they come together and that you can find a good price. However, purchasing your tickets at the door is possible the day off and right before the concert.
The concert hall is centered in downtown Chicago, right outside Millennium Park. Because of this venue, the Chicago Symphony Orchestra often holds free public concerts at the pavilion in Millennium Park. These concerts take place over the summer.
The concerts themselves are marvelous. Although the concert call may seem cramped (they have expanded it upwards and added second gallery), the sound of the orchestra carries clearly throughout. The concert hall has be updated with acoustical engineering to allow the best hearing situation possible for practically every seat. In addition, the energy and power of this group is just so great a dinky concert hall can't stop their sound.
The orchestra plays a wide variety of music (all classical of course), ranging from all eras. In addition, the orchestra also plays with singers and soloists. In addition, there are also several guest conductor series.
Besides the Chicago Symphony orchestra, there are also soloist and other music series. For instance there is the Sara Lee piano concert series, which features famous pianists from across the world coming to play at the concert hall. There is also a jazz concert series which features many of the world best and brightest jazz musicians, such as Wynton Marsalis, Dave Holland, and Marcus Roberts.
In summary, the Chicago Symphony Orchestra is definitely a must see. With famous performing artists playing with such a stellar and world-renown group, it would be a crime to visit Chicago without seeing them play live.