Entablature being called petrification. The structure of the entablature varies with the three classical orders: Doric, Ionic, and Corinthian. In each, the proportions of the subdivisions (architrave, frieze, cornice) are defined by the proportions of the column in the order. In Roman and Renaissance interpretations, it is usually approximately a quarter of the height of the column. Variants of entablature that do not fit these models are usually derived from them. Pure classical Doric entablature is simple. The architrave, the lowest band, is split, from bottom to top, into the guttae, the regulae, and the taenia. The frieze is dominated by
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)