Intercolumniation
In architecture, intercolumniation is the proportional spacing between columns in a colonnade, often expressed as a multiple of the column diameter as measured at the bottom of the shaft. In Classical, Renaissance, and Baroque architecture, intercolumniation was determined by a system described by the first-century BC Roman architect Vitruvius (Vitruvius, De architectura, iii.3.3-10). Vitruvius named five systems of intercolumniation (Pycnostyle, Systyle, Eustyle, Diastyle, and Araeostyle), and warned that when columns are placed three column-diameters or more apart, stone architraves break. According to Vitruvius, the Hellenistic architect Hermogenes (ca. 200 BC) formulated these proportions ("symmetriae") and perfected the Eustyle arrangement, which has an enlarged bay in the center of the façade. Standard intercolumniations The standard intercolumniations are: Pycnostyle One and a half diameters Systyle Two diameters Eustyle Two and a quarter diameters (and three diameters between middle columns front and rear); considered by Vitruvius to be the best proportion. Diastyle Three diameters Araeostyle Four or more diameters, requiring a wooden architrave rather than one of stone Araeosystyle Alternating araeostyle and systyle Vitruvius's definitions seem to apply only to examples with which he was acquainted in Rome, or to Greek temples described by authors he had studied. In the earlier Doric temples