Excitement is building in Washington in anticipation of Tuesday's inauguration of Barack Obama as the 44th president of the United States. An estimated one- to two million people are expected to witness Mr. Obama take the oath of office as the nation's first African-American president.

Hundreds of thousands of visitors are descending on Washington, hoping to witness a bit of history on Tuesday.

"It is a monumental historical event. There was no question of being here. It was just how we were going to get here and when," said one woman.

"We really wanted to come here and be a part of this because this is so exciting, and just being here is a real experience," said a young man, who is with a group of middle-school students from Iowa.

On the eve of his inauguration, President-elect Obama visited wounded soldiers at Walter Reed Medical Center in Washington.

Mr. Obama and Vice President-elect Joe Biden also paid tribute to the late civil rights leader, Dr. Martin Luther King, Junior. Monday is a national holiday in honor of the Reverend King's birthday. The incoming president and vice president joined volunteers working on a community renovation project during what is described as a day of national service.

All around Washington, final preparations are underway for Tuesday's inauguration.

Washington D.C. Mayor Adrian Fenty told NBC television that officials are ready to handle the huge crowds expected to come into the city to watch Mr. Obama take the oath of office and give his eagerly awaited Inaugural Address.

"It is going to be a fantastic day. The city welcomes everybody enthusiastically," he said.

Security is expected to be extremely tight.

Homeland Security Secretary Michael Chertoff told NBC authorities are mindful of the fact that Mr. Obama will make history as the nation's first African-American president.

"That will excite bad acts in a certain small percentage of the population who are bigoted, and so we want to be mindful that none of those people find their way into the area of proximity to the new president," said Chertoff.

Mr. Obama arrived in Washington on Saturday after a train trip from Philadelphia that paid historical tribute to President Abraham Lincoln's journey to his first inauguration in 1861.

On Sunday, well-known singers and actors paid tribute to Mr. Obama at the Lincoln Memorial in Washington.

The incoming president appeared to be aware that public expectations for his presidency are running high, given the economic and foreign policy challenges that await him.

"I will not pretend that meeting any one of these challenges will be easy. It will take more than a month, more than a year, and will likely take many," he said.

Later Monday, Mr. Obama will host separate dinners for Vice President-elect Biden, former Secretary of State Colin Powell and the man he defeated for the presidency, Senator John McCain of Arizona.

There will also be a free inaugural concert for young people to honor military families.

On Tuesday, Mr. Obama will go to the White House before the inaugural ceremony for coffee with President Bush, and the two men will then travel together to the Capitol building where Mr. Obama will take the oath of office and give his Inaugural Address.