Bike was locked to one of about 7 bike rakes full of other bikes just outside the Professional Building at Rush Medical Center on Paulina Street near Harrison St. Went inside for a doctor's appointment and my bike was gone when I came out. Security guards just inside the building were less than helpful, were not interested and didn't know what to do. Someone actually reported suspicious activity at this same time to a guard who did nothing to prevent the theft. This is a heavily trafficked area with people passing by constantly. I also found a silver road bike next to mine that was unlocked. I suspect that thieves took the lock but were spooked before they could take the bike. The security guards didn't want to take the bike that I brought inside the building. I just left it there with them and told them to keep an eye on it and wait for the owner.