The U.S. capital on Tuesday turned into a joyous sea of humanity as jubilant visitors swarmed into Washington from around the world to witness the historic moment when President-elect Barack Obama is inaugurated as the country's first black president.

Amid the toughest-ever security in any presidential inauguration, hundreds of thousands of people, bundled against frigid temperatures, streamed into the vast green at the National Mall and nearby viewing areas in the city center.

An estimated 2 million people were expected to bear witness to the first change of administration since the September 11 attacks in 2001.

Beginning a day full of hectic inauguration activities, Obama and wife Michelle appeared at St. John's Episcopal Church near the White House for an inaugural morning prayer service.

Then, they were greeted by outgoing President George W. Bush at the White House, who led them on a brief tour on their home for the next four years, before taking a short ride to the U.S. Capital for the historic inauguration of America's 44th president.

(Xinhua News Agency January 20, 2009)