As an estimated two million people converge on Washington Tuesday, the largest inaugural security operation in history will work to protect Barack Obama as he takes the Oath of Office.

In total, 58 federal, state and local agencies are working together to protect Obama.

The inauguration festivities will begin at 10 a.m. ET, with Obama to be sworn in as president around noon. Nearly 250,000 people have tickets to attend the inauguration.

After the inauguration, Obama will escort outgoing President George Bush to a departure ceremony before attending a luncheon in the Capitol's Statuary Hall.

The 56th Inaugural Parade will then make its way down Pennsylvania Avenue from the Capitol to the White House.

Security expert Alan Bell said authorities have been planning for the inauguration for well over a year.

"All the roads are going to be closed down, there's going to be a set route and if anything happens he will be evacuated into his vehicle if he's on foot," Bell told CTV Newsnet in a recent interview.

If Obama is already in the vehicle, Bell said the president "will then go back to an emergency rendezvous point where he will be extricated from the vehicle."

Obama's limousine, nicknamed "The Beast," boasts heavy armour, run-flat tires, bulletproof glass and has a completely sealed interior in case of a biological or chemical attack.

Meanwhile, thousands of extra police, military troops and law enforcement agents will be on hand to provide extra security.

There will also be plainclothes officers in the crowds, one for every 100 people.

"They'll be looking for people who are getting over exuberant and trying to get closer to the president," Bell said.

"They'll also be looking for people who dislike the president and what he stands for."

Bell said the Washington will effectively be shut down for a number of hours and no aircraft will be allowed to fly over the city -- except for fighter jets on air patrol.

Meanwhile, all of the buildings in the area will be closed for at least 24 hours and will have Secret Service snipers stationed inside them, Bell said.

Intelligence officials have not received any inauguration-specific threats but say the significance of swearing in Obama, the first black president, make it a vulnerable target.

According to The New York Times, officials in the District of Columbia are expecting the bill for Tuesday's inauguration to hit $50 million.

On Monday, military personnel were already patrolling the streets of Washington, the newspaper reported. But officials said everything seemed calm, according to FBI spokesperson Richard Kolko.

"The city and the people seem to be in a good mood and good spirits," he told The Times. "Security is going well, that's what all the planning is for."

With files from The Associated Press