HOK (formerly Hellmuth, Obata + Kassabaum) is a global design, architecture, engineering and planning firm.
As of 2013, HOK is the largest U.S.-based architecture-engineering firm and the third-largest interior design firm. The firm maintains more than 1,600 professional staff across a global network of 24 offices and is active in all major architectural specialties. Its senior leaders are located in several different locations across the world. 360 Architecture has joined global design, architecture, engineering and planning firm HOK.