Customer Hines Holder Construction Location Oklahoma City, Oklahoma Services Provided BAS Overview of Project It has been ten years since ES2 helped build the Devon Energy Center, also known as Devon Tower. Devon Tower is a 50-story corporate skyscraper and the most noticeable building in the Oklahoma City skyline, and it holds the distinction of being the tallest building in Oklahoma. Construction began in October 2009, and the building was completed in October 2012. The tow