The RSA–BankTrust Building, originally the First National Bank Building, is a 34 story, 424-foot (129 m) International Style office tower located in downtown Mobile, Alabama. Most recently known as the AmSouth Bank Building, it had been named in honor of its largest tenant until 2006, AmSouth Bancorporation. It was renamed the GM Building by its new owner, Retirement Systems of Alabama, in 2009. Following a lease agreement with BancTrust Financial Group and its community bank subsidiary, BankTrust, it was renamed again. BancTrust Financial Group is the only publicly traded bank holding company headquartered in Mobile.