Skidmore, Owings and Merrill LLP (SOM) is an architectural and engineering firm that was formed in Chicago in 1936 by Louis Skidmore and Nathaniel Owings; in 1939 they were joined by John O. Merrill. They opened their first branch in New York City, New York in 1937. SOM is one of the largest architectural firms in the world and their primary expertise is in high-end commercial buildings. SOM have built several of the tallest buildings in the world, including the John Hancock Center (1969, second tallest in the world when built), Sears Tower (1973, tallest in the world for over twenty years), and Burj Khalifa (2010, currently the world’s tallest building). They were recently awarded the bid to design a Green Tech City in Vietnam.