In architecture, intercolumniation is the spacing between columns in a colonnade

Colonnade

In classical architecture, a colonnade denotes a long sequence of columns joined by their entablature, often free-standing, or part of a building....

, as measured at the bottom of their shafts. In classical

Classical architecture

Classical architecture is a mode of architecture employing vocabulary derived in part from the Greek and Roman architecture of classical antiquity, enriched by classicizing architectural practice in Europe since the Renaissance...

, Renaissance

Renaissance architecture

Renaissance architecture is the architecture of the period between the early 15th and early 17th centuries in different regions of Europe, demonstrating a conscious revival and development of certain elements of ancient Greek and Roman thought and material culture. Stylistically, Renaissance...

, and Baroque architecture

Baroque architecture

Baroque architecture is a term used to describe the building style of the Baroque era, begun in late sixteenth century Italy, that took the Roman vocabulary of Renaissance architecture and used it in a new rhetorical and theatrical fashion, often to express the triumph of the Catholic Church and...

, intercolumniation was determined by a system devised by the 1st century BC Roman

Ancient Rome

Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 architect Vitruvius

Vitruvius

Marcus Vitruvius Pollio was a Roman writer, architect and engineer, active in the 1st century BC. He is best known as the author of the multi-volume work De Architectura ....

. Vitruvius compiled standard intercolumniations for the three classical Greek orders, expressed in terms of the column diameter, twice the Vitruvian module

Vitruvian module

A module is a term that was in use among Roman architects, corresponding to the semidiameter of the column at its base. The term was first set forth by Vitruvius , and was employed by architects in the Italian Renaissance to determine the relative proportions of the various parts of the Classical...

, and he warned that when columns are placed three column-diameters apart or more, stone architrave

Architrave

An architrave is the lintel or beam that rests on the capitals of the columns. It is an architectural element in Classical architecture.-Classical architecture:...

s break.

Standard intercolumniations

The standard intercolumniations are:
Pycnostyle : One and a half diameters
Systyle : Two diameters
Eustyle : Two and a quarter diameters, considered by Vitruvius to be the best proportion
Diastyle : Three diameters
Araeostyle : Four or more diameters, requiring a wooden architrave

Architrave

An architrave is the lintel or beam that rests on the capitals of the columns. It is an architectural element in Classical architecture.-Classical architecture:...

rather than one of stone
Araeosystyle : Alternating araeostyle and systyle