The term 'Architectural Order' refers to a system of classical architecture that is characterized by specific proportions, column styles, and entablatures. The two most common orders are the Ionic and Doric orders. The Ionic order is characterized by its volutes, or spiral-like decorations, on the capitals of its columns, while the Doric order is characterized by its plainer capitals and lack of ornamentation. Both orders have been used in many famous buildings throughout history, such as the Parthenon in Athens.