Originally a marquee - or marquise - was a cloth canopy set up before a tent or building for protection from the rain and sun. They were found especially on boats. Architecturally a marquise is a permanent protective canopy often of metal and glass projecting over an entrance, a stoop or a window. It is both an architectural ornament and a useful shelter. A small projecting roof, it can be called a marquise only if it is a metal structure paned with glass (either clear or cathedral glass) with an often curved belt above and supported by brackets. Marquises can be quite elaborate, decorated with wrought iron ornaments like volutes, often adorned with beautiful lanterns. It generally reaches up towards the sky, so rain runs back down towards the gutter against the wall and falls down the drainpipe often referred to as columns.
It is hard today to find references of the first marquises, but there are some in the Renaissance style that are elaborately ornate. Some more massive and heavily decorated are definitely Louis XIV in style. Louis XV marquees were elegant with curved belts and highly adorned brackets, while the Louis XVI style developed a high level of refinement in the design of their broad glass panes and artistry of the wrought iron work. Reserved to inner court yards until the end of the 19th and early 20th centuries, Parisian facades were embellished with extraordinary wrougt iron masterpiece marquises as the rigid Haussmanian architectural code subsided. They were placed above the entrances of homes and hotels, theaters and restaurants but most famously above the stairways of Hector Guimard’s Metro stations
Yves Lucas, Journey through the Marquees, éd. With the same title Paris, 2002.