The Chicago Opera House, (constructed in 1884–5) was a theater complex in Chicago, Illinois, USA, designed by the architectural firm of Cobb and Frost. The Chicago Opera House building took the cue provided by the Metropolitan Opera of New York as a mixed-used building: it housed both a theater and unrelated offices, used to subsidize the cost of the theater building. The theater itself was located in the middle of the complex and office structures flanked each side. The entire complex was known as the "Chicago Opera House Block," and was located at the Southwest corner of West Washington Avenue and North Clark Street.