 The center section of the dirt and sawdust floor was replaced with a concrete floor in 1918, and at the same time some of the original pine benches were replaced with 586 "opera chairs".In the 1970s, about the time the building was placed on the National Register of Historic Places, it was in a dilapidated condition.A combination of two factors—the NRHP designation and the decision of the Colorado Music Festival to call the Chautauqua Auditorium its home—provided the impetus for a general renovation of the structure.