Intercolumniation was determined from a system codified by the 1st-century BC Roman architect Vitruvius.
Vitruvius established five standard measurements for intercolumniation:
One and a half diameters
Two and a quarter diameters, considered by Vitruvius to be the best proportion
Four or more diameters, requiring a wooden architrave rather than one of stone
Alternating araeostyle and systyle