Constructed in 1961 for use by the Pittsburgh Civic Light Opera (CLO), it was the brainchild of department store owner Edgar J. Kaufmann. It was the first retractable roof major-sports venue in the world, covering , constructed with nearly 3,000 tons of Pittsburgh steel and supported solely by a massive long cantilevered arm on the exterior. Even though it was designed and engineered as a retractable-roof dome, the operating cost and repairs to the hydraulic jacks halted all full retractions after 1995, and the roof stayed permanently closed after 2001. The first roof opening was during a July 4, 1962, Carol Burnett show to which she exclaimed "Ladies and Gentlemen...I present the sky!"