Today, an estimated 800,000 people crowded onto the National Mall to witness the swearing-in of President Barack Obama. The inauguration is the 57th in the United States' history and follows the November 6 reelection of Barack Obama, America's 44th President. View more photos at the #inauguration2013, #inaug2013 and #CNN hashtags, and by clicking the blue location link above. Photo by @wchong25.