Louis Kahn's Salk Institute for Biological Studies brings a theoretical clarity to the way modern architecture orders functional complexity: the separation of 'servant' and 'served' spaces. A laboratory wants flexible, uninterrupted work areas; but these areas demand an 'infrastructure forest' of ventilation ducts, pipes, cables, and services.

Kahn sharply separates the two. The continuous, columnless laboratory floors are the 'served' space; immediately above each laboratory floor he places a full services floor nearly a storey high that a person can walk through (carried on Vierendeel trusses) — this is the 'servant' space. All pipes and ducts gather in these intermediate floors; the laboratories remain wholly free, flexible, and divisible, and maintenance or replacement of services is done without ever interrupting research. Function and infrastructure are cleanly separated in architecture.

But what truly makes Salk unforgettable is the courtyard between the two symmetrical laboratory blocks. Kahn had planned a garden here, but his consultant, the architect Luis Barragán, said 'do not put even a leaf; let it be a plaza.' The result is a wholly empty, travertine-paved platform with a thin water channel running down its middle — a void opening directly to the horizon of the Pacific Ocean. Salk is one of the most revered works of contemporary architecture, uniting the rigorous engineering order of function with the spiritual silence of space in a single building.