In a defining moment in US history, Barack Hussein Obama was today sworn in as the first black president in a country hungry for change after George W Bush's divisive wars in two distant lands and the economic troubles that shook the country and the rest of the world.
Climaxing the unlikeliest of journeys to the White House, the 47-year-old African-American who has raised unprecedented expectations worldwide was administered the oath of office as the 44th president by Chief Justice John G Roberts Jr on a chilly morning at 12:06 PM (2236 IST ), 12 minutes behind schedule, on the steps of the West Front of the Capitol Hill where the US Congress sits.
Significantly before Obama, a president had never been sworn in by a chief justice he voted against. Indian Ambassador to the US Ronen Sen was among those present at the costliest inaugurals estimated to have cost 170 million dollars.
Braving icy temperatures, an estimated two million people from all over the country and some from outside thronged Washington to watch the charismatic Democrat's tryst with history and roared in approval after he took oath, nearly 11 weeks after winning the November4 presidential elections defeating the Republican candidate John McCain.
Shattering racial barriers as the first Afro-American head of America, Obama, the son of a black Kenyan and white mother from Kansas, took his oath placing hands on the same Bible used at the 1861 inauguration of Abraham Lincoln, whose Emancipation Proclamation ended slavery.
Bush, who leaves Washington as one of the nation's most unpopular and divisive presidents after a eight-year rule, watched the first change of guard since 2001 along with his wife Laura. Former presidents Jimmy Carter, George H Bush and Bill Clinton were also present.
The incoming First Lady Michelle Obama carried to the platform the Bible on which the country's fourth youngest president placed his left hand, and repeated the 35-word oath of office with right hand raised promising to "preserve, protect and defend the Constitution of the United States "adding "so help me God" at the end. Obama decided to use his full name--Barack Hussein Obama--for the swearing-in.
Before the historic Obama oath, Joseph Biden, the Democrat's running mate, was sworn in as Vice President. Outgoing Vice President Dick Cheney pulled a muscle in his back and was in a wheelchair for the inauguration.
Obama,father of two daughters, opted for a classic politician's outfit of black suit, red tie and a white shirt while Michelle wore a coat and a matching shift dress in lace brocade in golden hues. In a robust fashion move, neither Obamas wore a hat or scarf to protect them against harsh winter weather.
Security was unprecedented in Washington in the biggest and most advanced inaugural security operation ever seen to counter any potential terror threat, as Obama, who exploded into the national stage just five years back, drove in a new heavily armoured black Cadillac limousine.
More than 12,500 active troops and military reservists, thousands of metropolitan police as well as personnel from 57 departments around the nation descended on Washington for what the Department of Homeland Security has designated a national special security event.
Obama, a gifted and inspirational speaker whose ascendancy to the top office electrified the world, takes over a nation gripped by uncertainty after Bush's eight divisive years in the White House, an era that witnessed the Sept. 11, 2001 terror attacks, the beginning of wars in Afghanistan and Iraq and an economic collapse not seen since the 1930s Great Depression.
Miles of black iron security fencing were laid out along the parade route and much of the National Mall stretching from Capitol Hill, built by slave labour, to the Lincoln Memorial, where Martin Luther King, Jr. Spoke in 1963 of a dream of racial unity in the memorable " I have a dream...Speech".
More than 10,000 people from all 50 states including bands and military units follow Obama and Biden from the Capitol along the 2.4-km inaugural parade route down Pennsylvania Avenue., concluding at a bullet-proof reviewing stand in front of the White House.
One official who will miss out on the celebrations is US Defense Secretary Robert Gates, who remained at an undisclosed location as the "designated successor" in the event of a catastrophe.
The inauguration day began early for Obama and his wife Michelle. Together with Biden and his family, they attended a church service at St John's Epsicopla Church.
This was followed by coffee at the White House with outgoing president George W Bush and Vice-President Dick Cheney. The group then travelled to the Capitol Hill along a packed route.
Marching bands, military veterans, union workers and schoolchildren were to then join a parade down Pennsylvania Avenue to the White House for Obama to take up the reins of power in the Oval Office and his place in history.
In less than five years, Obama rose from a little-known Illinois state lawmaker to the nation's highest office, persuading Americans that despite his relative inexperience, he could turn around the economy, end the Iraq war and restore U.S. Standing in the world.
Culminating four days of celebration, Obama and Vice President-elect Joe Biden began the day with a traditional morning worship service at St. John's Episcopal Church, across Lafayette Park from the White House and were due toend it with dancing and partying at 10 inaugural balls lasting deep into the night.