De architectura is a treatise on architecture written by the Roman architect and military engineer Marcus Vitruvius Pollio and dedicated to his patron, the emperor Caesar Augustus, as a guide for building projects. As the only treatise on architecture to survive from antiquity, it has been regarded since the Renaissance as the first known book on architectural theory, as well as a major source on the canon of classical architecture.

The Doric order was one of the three orders of ancient Greek and later Roman architecture; the other two canonical orders were the Ionic and the Corinthian. The Doric is most easily recognized by the simple circular capitals at the top of the columns. Originating in the western Doric region of Greece, it is the earliest and, in its essence, the simplest of the orders, though still with complex details in the entablature above.