The Parthenon is principally an example of the Doric architectural order. Its exterior is a monumental Doric temple, recognized by its sturdy columns, plain capitals, and entablature of alternating triglyphs and metopes.
The building represents the mature Classical form of the Doric order and is often treated as one of its finest achievements. It is unusually large and uses eight columns across each short end and seventeen along each long side, an arrangement known as octastyle and peripteral. The architects also refined the structure with subtle optical adjustments, including slightly curved horizontal lines and carefully managed column spacing.
The Parthenon is not architecturally “pure” in every detail. Its continuous inner frieze is Ionic in character, and its interior included Ionic columns. That mixture sometimes causes confusion, but the temple’s primary order is still Doric because its overall exterior design and principal colonnade follow Doric conventions.
It should also not be called Corinthian or Composite. Those orders developed distinctive capitals and became especially prominent later, particularly in Roman architecture.