Barack Obama is to be publically sworn in for his second term as US president.
Hundreds of thousands are expected in Washington for the event, which will feature music from Beyonce, parades, black tie balls and tight security.
They will crowd onto the Mall leading to Congress to see their president sworn in on the steps of the Capitol.
Mr Obama was officially inaugurated in a small White House ceremony on Sunday, as the US Constitution requires the president be sworn in by 20 January.
In the famous Blue Room, he rested his hand on a Bible used for many years by his wife’s family and vowed “to preserve, protect and defend the Constitution of the United States”.
He will repeat those words at Monday’s public inauguration, in which he is also expected to use a speech to set out his plans for the next four years.
He is then expected to follow the recent tradition of walking through the crowds for at least some of the way back to the White House.
Vice-President Joe Biden, who was also sworn in on Sunday – will repeat his oath publicly as well.
Thousands of workers and volunteers have been working to finish construction for Monday’s celebrations, with white tents, trailers and generators being set up along the Washington Mall’s parade route as nearby buildings were adorned with red, white and blue bunting.
In 2009, nearly two million people crammed into Washington to witness President Obama’s first inauguration.
Four years on, the mood is unlikely to match that excitement, says the BBC’s Ben Wright in Washington.
But, he adds, the second inauguration of America’s first black president is a moment many will not want to miss.