A pediment is a triangular gable that forms the end of the roof slope over a portico, which is an area with a roof supported by columns leading to the entrance of a building. It is a decorative element that crowns the front of a Greek temple and is placed above the horizontal structure of the cornice or entablature if supported by columns. The triangular wall surface of the pediment, called the tympanum, rested on an entablature carried over the columns and was often decorated with sculpture. The pediment is found in classical Greek temples, Etruscan, Roman, Renaissance, Baroque, Rococo, Neoclassical, and Beaux-Arts architecture. Pediments are also used decoratively over a doorway or window. The pediment is a defining trait of Classical architecture, which emphasizes the overall harmony and mathematical relationship between various geometric elements.