What is parti in architecture?

In architecture, a parti is an organizing thought or decision behind an architect's design, presented in the form of a parti diagram, parti sketch, or a simple statement.[1][2] The term comes from 15th century French, in which "parti pris" meant "decision taken."[3]

The development of the parti frequently precedes the development of plan, section, and elevation diagrams.[4]

Producing a quick sketch (esquisse) of the parti was a critical part of architectural training at the Beaux-Arts de Paris during the 19th and early part of the 20th Century.[5]

In architecture school during the 1900s in the United States, one would have understood the term ‘parti’ as the "main idea" for the planimetric layout of a building. Its roots in the American architectural education system are derived from the Beaux-Arts de Paris. The word "parti" refers to the concept of ‘parti pris’, and refers to the main ‘idea’ of the organizing principle that is embodied in a design and often expressed by a simple geometric diagram. The "parti" often expresses the essence of an architectural design reduced to its essence.[6]

The parti [6] of the Lonja del Comercio building in Havana (in plan) is a perfect square and based on the classic 9 square problem that was used, [1] [7][a] among others, by Peter Eisenman to design some of his houses [2] and Andrea Palladio in the design of many of his villas. [3] [8] [b][9] [4]