'Medium Cool' (1969) The International Amphitheatre at 4220 S. Halsted St., razed in 1999, was an important part of life in Chicago for decades. It was the first home of the Chicago Bulls and hosted livestock shows, the Chicago Auto Show and five national political conventions, including the tumultuous 1968 Democratic Convention. Watching the powerful 1969 film "Medium Cool" the other day, I was able to go inside the Amphitheatre and see the Democrats, including Chicago Mayor Richard J. Daley, father of the city's present chief executive, in action at that '68 convention. At one point, the central character, a television cameraman played by Robert Forster, is standing in the upper reaches of the arena looking out at the constantly moving, placard-waving political crowd while directly below him the tiny figure of Daley is making an address. It's a true you-are-there moment, one of many in a documentary-like film that was revolutionary in both technique and purpose. In the movie, director Haskell Wexler is telling a fictional story against the backdrop of real Chicago -- the real Uptown neighborhood with its real poverty; the real South Side with real Black Power militants, such as artist Jeff Donaldson; and the real Grant Park where real police officers were beating up real protesters while one of Wexler's actors (Verna Bloom, in a bright yellow dress) moves along the edges of the violence. "Medium Cool" is a time capsule that records more than a building that's gone (the Amphitheatre) and another that's been drastically altered (Soldier Field). It documents, to a degree unprecedented in a feature film, Chicagoans at a quintessential moment in the city's history. It's a Chicago that once was -- and a time that has done much to shape our own.