Bronze

Bronze is an alloy of copper and tin, occasionally with other elements added, used architecturally for doors, statuary, ornamental fittings and, since the twentieth century, structural and cladding elements on prestige buildings, valued for its rich color, durability and the way it develops a protective patina similar to copper's. Its use in monumental doors and sculpture dates to antiquity, and in modern architecture it became closely associated with high-end curtain-wall and window framing, most famously the bronze mullions and spandrels of Ludwig Mies van der Rohe's Seagram Building, where its warm, weathering surface was chosen explicitly over cheaper, more inert metals.