One AT&T Plaza, formerly known as One Bell Plaza and One SBC Plaza, is a 37-story high-rise in Downtown Dallas, located adjacent to the Akard Street Mall. It serves as headquarters for Southwestern Bell Telephone, who operates as "AT&T Southwest". The building is 580 feet (177 m) tall and was constructed in 1984. Currently, it is the 13th-tallest building in the city. It is part of a four structure complex owned by AT&T.