The 50-story Devon Energy Building, the tallest building completed in the U.S. this year, celebrated is official opening on Tuesday. The 844-foot (257-meter) Devon Tower has been open since March, but yesterday marked the invitation-only commemoration ceremony.

Find previous CTBUH coverage over Devon Tower's completion here.

The 1.8 million-square-foot complex in downtown Oklahoma City will contain an estimated 2,200 employees and contractors every day, according to local media.

The complex includes a 285-seat auditorium, a park, two restaurants, a coffee shop and the tower. Construction on the $750 million tower began in 2009.