HOK

Founding

HOK was established in St. Louis, Missouri, in 1955. The firm is named for its three founding partners: George F. Hellmuth, Gyo Obata and George Kassabaum, all graduates of the School of Architecture at Washington University in St. Louis.

The practice's first building designs were schools in St. Louis suburbs, and St. Thomas Aquinas High School in Florissant was the first independent school designed by the firm. Another prominent school they designed was the Saint Louis Priory School.

Early years

By the mid-1960s, the firm began to open additional offices, starting with San Francisco in 1966 for the design of a library at Stanford University and Dallas in 1968 for the master planning and design of Dallas/Fort Worth International Airport. Also in 1968, HOK launched its interior design practice. That year, HOK expanded into Washington, D.C., after winning the commission to design the Smithsonian National Air and Space Museum. In 1973, HOK established a presence in New York by acquiring Kahn & Jacobs, designers of many New York City skyscrapers. By the 1970s, the firm was operating internationally and in 1975 the firm was named as architect of the $3.5 billion King Saud University in Riyadh, at the time the single largest building project in the world. In 1979, George Kassabaum was elected into the National Academy of Design as an Associate Academician.

In 1983, HOK formed HOK Sport Venue Event, a subsidiary devoted entirely to designing sport stadiums, arenas, and convention centers, an architectural boom market at the time. In January 2009, the Board of HOK Group, Inc. and managers of HOK Sports Facilities, LLC transferred ownership of HOK Sport to leaders of that practice. The company became an independent firm, and rebranded itself as Populous.

Expansion and acquisitions

HOK's first office outside the US opened in Hong Kong in 1984, and the second in London in 1987, a practice that would be expanded in 1995 by merging with the British architectural practice Cecil Denny Highton.

The firm expanded into China in 2013, when it acquired the New York and Shanghai offices of hospitality design firm BBG-BBGM, creating one of the world's largest interior design firms, although BBG-BBGM's office in Washington, D.C., continues to operate as BBGM. By 2007, international work represented more than 40% of HOK's annual revenue.

As of July 2026, HOK operates 28 offices across North America, Europe, and Asia, including in Hong Kong, Beijing and Shanghai in China; Dubai in the Middle East; Mumbai, India; and Toronto, Canada, where it established its first offices in 1997 with the acquisition of Urbana Architects.

Other domestic acquisitions include Caudill Rowlett Scott based in Houston, Texas, in November 1994, adding offices in Houston and Atlanta. The purchase of 360 Architecture in January 2015, a 200-person, Kansas City-based firm, gave the group additional capabilities in the design of stadiums, ballparks and arenas. That acquisition enabled HOK to launch a new global Sports, Recreation, and Entertainment design practice after the breakaway of Populous, and to open new offices in Kansas City and Columbus, Ohio (which has since closed). In May 2026, HOK acquired Rossetti Architects, a Detroit-based architecture firm.