Former Pittsburgh Steelers and Baltimore Ravens tackle Alejandro Villanueva is retiring.The Ravens announced his decision Wednesday.Villanueva played six years with Pittsburgh before joining the Ravens last season. The two-time Pro Bowler started every game after his rookie year.Villanueva, a West Point graduate, was an active member of the U.S. Army before his NFL career. He was 26 when he made his NFL debut in 2015.