Barack Obama has left the White House for the final time as president.
The 44th president of the United States left his home of the past eight years in the company of the man who will succeed him, Donald Trump.
Obama and First Lady Michelle Obama hosted Trump and his wife Melania at the traditional morning tea on Friday, before they left for the Capitol building for the swearing in at midday (0400 AEDT).
Earlier, Obama took a final stroll from the Oval Office through the Rose Garden as a sitting president.
He told reporters he's feeling nostalgic on his final day as president.
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He said his final message to the American people is "thank you."
Obama also left a letter for his successor in the Oval Office before departing the White House - as is the tradition from one president to the next.
However, the White House is providing no details about what Obama conveyed to Trump in the note.
Obama campaigned vigorously against Trump. But the president and president-elect have had regular phone conversations since the election, with the president offering guidance and advice.
Obama also bid farewell from the official presidential Twitter account.
"It's been the honor of my life to serve you."
He told followers he was "still asking you to believe - not in my ability to bring about change, but in yours."
The president is also asking people to share their thoughts about the focus of his new foundation's work.
He says: "I won't stop; I'll be right there with you as a citizen, inspired by your voices of truth and justice, good humor, and love."
The Obamas are asking the public to help them develop projects for his new presidential centre on Chicago's South Side.
The Obamas are starting up a foundation website - Obama.org.
The White House said members of the residence staff had presented the Obamas with two American flags that were flown atop the building.
One of the flags was flown on the first day of Obama's presidency. The other was flown on his final morning as president.
