Though most of the show's production takes place on soundstages in southern California, the long-running NBC drama "ER" has traveled to Chicago numerous times for on-location shoots in the Windy City. Now, after 15 years on the air, "ER" is shooting its series finale. And once again, the crew is back in Chicago for some final on-location shooting. Here's a look at some of "ER" on-location shoots in Chicago over the years.

Click here to watch clips from the 'ER' finale and some classic episodes.