Doric order The Roman architect Vitruvius, following contemporary practice, outlined in his treatise the procedure for laying out constructions based on a module, which he took to be one half a column's diameter, taken at the base. An illustration of Andrea Palladio's Doric order, as it was laid out, with modules identified, by Isaac Ware, in "The Four Books of Palladio's Architecture" (London, 1738) is illustrated at Vitruvian module. According to Vitruvius the height of Doric columns is six or seven times the diameter at the base. This gives the Doric columns a shorter, thicker look than Ionic columns, which have 8:1
Bodleian Library the "Old Schools Quadrangle", or the "Old Library") was built between 1613 and 1619 by adding three wings to the Proscholium and Arts End. Its tower forms the main entrance to the library, and is known as the Tower of the Five Orders. The Tower is so named because it is ornamented, in ascending order, with the columns of each of the five orders of classical architecture: Tuscan, Doric, Ionic, Corinthian and Composite. The three wings of the quadrangle have three floors: rooms on the ground and upper floors of the quadrangle (excluding Duke Humfrey’s Library, above the Divinity School)