An opera window is a small fixed window usually behind the rear side window of an automobile. They are typically mounted in the C-pillar of some cars. The design feature was popular during the 1970s and early 1980s that was adopted by domestic U.S. manufacturers most often with a vinyl roof. The origin was from around 1915 "opera" vehicles with occasional collapsible seating for extra passengers. The opera window was also a feature on "formal roof" and limousine models with higher than normal roof to accommodate passengers with top hats.