Barack Obama has seemingly left a note for Donald Trump in the Oval Office as he walked out for the final time.
The Obamas greeted the Trumps at the grand North Portico, the column-lined entrance facing Pennsylvania Avenue, and exchanged pleasantries.
Mr Obama appeared in good spirit as he cracked a joke, switching the order of the two couples, as they posed for pictures.
When Mr Obama entered the Oval Office in eight years ago, George W. Bush had left him a letter, which congratulated him and provided words of support.
“Very few have had the honour of knowing the responsibility you now feel. Very few know the excitement of the moment and the challenges you will face,” Mr Bush's letter said.
“There will be trying moments. The critics will rage. Your 'friends' will disappoint you. But, you will have an Almighty God to comfort you, a family who loves you, and a country that is pulling for you, including me.
“No matter what comes, you will be inspired by the character and compassion of the people you now lead,” Mr Bush wrote.
It is tradition for the outgoing President to leave a note behind for his successor and Mr Obama placed his letter on the Resolute desk ahead of Mr Trump’s inauguration.
As he left the Oval Office, Mr Obama said he felt nostalgic and when asked for his last words to the American people he said “thank you”, AFP reported.
Violent protests have broken out in Washington ahead of the inauguration as police clashed with demonstrators.
Some have been filmed smashing windows and carrying flags bearing the anarchist symbol.
Police have responded with tear gas, pepper spray, water cannons and stun grenades to disperse the crowds.
