U.S. President Barack Obama took the oath of office at his public swearing-in on Monday (January 21). Obama raised his right hand and was sworn in by Supreme Court Chief Justice John Roberts outside the U.S. Capitol at 11:51 a.m. ET (1651 GMT). He placed his left hand on two Bibles - one once owned by Abraham Lincoln and the other by Martin Luther King, Jr. It was the second time he took the oath in 24 hours.