Intercolumniation

[2] 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.

200 BC) formulated these proportions ("symmetriae") and perfected the Eustyle arrangement, which has an enlarged bay in the center of the façade.

[4] The standard intercolumniations are:[5] 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 the intercolumniation is sometimes less than one diameter, and it increases gradually as the style developed; thus in the Parthenon it is 1⁠1/4⁠, in the Temple of Diana Propylaea at Eleusis, 1⁠1/4⁠; and in the portico at Delos, 2⁠1/2⁠.

Thus in the temple of Apollo Branchidae, where the columns are slender and over 10 diameters in height, the intercolumniation is 1⁠3/4⁠, notwithstanding its late date, and in the Temple of Apollo Smintheus in Asia Minor, in which the peristyle is pseudodipteral, or double width, the intercolumniation is just over 1⁠1/2⁠.