Photo gallery: Obama takes oath of office for second term in quiet ceremony

WASHINGTON - A greyer and more solemn-looking US President Barack Obama officially began his second term on Sunday, following a private oath-taking ceremony at the White House. 

The quiet ceremony, administered by Supreme Court Chief Justice John Roberts, marked a sharp contrast with the electrifying atmosphere in Washington four years ago when Mr Obama became the first African-American to be sworn-in as the commander-in-chief of the United States.