The World's Largest Architecture Firms

Vanessa Quirk discusses the results of Building Design's annual listing of the largest architecture firms in the world. The architecture and engineering behemoth Aecom has claimed top spot (up from number 2 last year) with 1,370 employees.

1 minute read

February 13, 2013, 5:00 AM PST

By Jonathan Nettler @nettsj


"Building Design has released their annual ranking, The WA100, of the world’s largest architecture firms. Coming in the #1 spot (up from #2 last year) is Aecom, who, with 1,370 employees worldwide, narrowly outranked Gensler (with 1,346 employees). Completing the top three was IBI Group (1,129 employees). Aecom, Gensler, and Japanese-based firm Nikken Sekkei (ranked #4) were the top 3 earners of 2012, each making over $400 million US Dollars in Fee Income."

"Interestingly," notes Quirk, "the only firms to grace both the Top 10 list and Building Design’s survey of the Top 5 Most Admired Firms of 2012, were Gensler (#2 Largest; #4 Most Admired) and Foster & Partners (#10 Largest; #1 Most Admired). Zaha Hadid Architects (who shared the number 5 Most Admired spot with Rogers Stirk Harbour & Partners, ranked as the 45th largest firm)."

Monday, February 11, 2013 in Arch Daily

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Get top-rated, practical training

Red 1972 Ford Pinto with black racing stripes on display with man sitting in driver's seat.

Analysis: Cybertruck Fatality Rate Far Exceeds That of Ford Pinto

The Tesla Cybertruck was recalled seven times last year.

July 2, 2025 - Mother Jones

Close-up of park ranger in green jacket and khaki hat looking out at Bryce Canyon National Park red rock formations.

National Parks Layoffs Will Cause Communities to Lose Billions

Thousands of essential park workers were laid off this week, just before the busy spring break season.

February 18, 2025 - National Parks Traveler

Paved walking path next to canal in The Woodlands, Texas with office buildings in background.

Retro-silient?: America’s First “Eco-burb,” The Woodlands Turns 50

A master-planned community north of Houston offers lessons on green infrastructure and resilient design, but falls short of its founder’s lofty affordability and walkability goals.

February 19, 2025 - Greg Flisram

Screenshot of shade map of Buffalo, New York with legend.

Test News Post 1

This is a summary

0 seconds ago - 2TheAdvocate.com

Red 1972 Ford Pinto with black racing stripes on display with man sitting in driver's seat.

Analysis: Cybertruck Fatality Rate Far Exceeds That of Ford Pinto

The Tesla Cybertruck was recalled seven times last year.

18 minutes ago - Mother Jones

test alt text

Test News Headline 46

Test for the image on the front page.

March 5 - Cleantech blog