Joe Biden said "welcome home" as Donald Trump arrived at the White House for tea ahead of his historic inauguration as the 47th president of the United States.
The Republican is returning to the presidency after his historic victory in last year's election sealed perhaps the most remarkable political comeback in US political history, despite being a convicted felon.
Mr Trump is expected to issue a flurry of executive orders on day one of his second administration, including declaring a national emergency at the border with Mexico and ending birthright citizenship.
Follow live: Famous faces arrive for swearing-in ceremony
As the inauguration events got under way, the two men were joined by Mr Biden's wife Jill and incoming first lady Melania for the tea, which is traditionally held to welcome the new president.
The meeting was a stark contrast to four years ago, when Mr Trump refused to acknowledge Mr Biden's election victory or attend his inauguration.
Afterwards, the incoming and outgoing presidents set off for the Capitol in the same car.
Church appearance this morning
Mr Trump was seen for the first time in public today when he arrived at St John's Episcopal Church in Washington DC for a prayer service at 8.45am local time (1.45pm UK time).
The service at the historic church, located across from the White House, was the start of a momentous day for Mr Trump as millions of people around the world watch on.
The Republican and his wife sat in the front row with their son Barron, 18, to their left, and incoming vice president JD Vance and his wife Usha to their right.
Former British prime minister Boris Johnson, Facebook chief executive Mark Zuckerberg and Amazon boss Jeff Bezos were also spotted sitting in the same row as each other in the church.
The service lasted around 30 minutes.
Afterwards, Mr Trump briefly returned to Blair House, often referred to as the "President's Guest House", where he stayed on Saturday and Sunday.
Inauguration ceremony to be held indoors
Mr Trump's swearing-in ceremony will take place inside the Capitol Rotunda after it was moved indoors because of what is forecast to be the coldest inauguration day in 40 years.
It is not clear how the ceremony will be adapted to the setting, but only a fraction of the originally expected crowd will be allowed in.
Mr Vance is expected to be sworn in at 11.25am local time (4.25pm UK time).
The 40-year-old will take the oath read by Supreme Court Justice Brett Kavanaugh on a bible given to him by his great-grandmother.
Mr Trump is expected to take the oath at around 11.40am local time (4.40pm UK time).
Read more:
What does Trump 2.0 mean for you?
What will Trump do first on inauguration day?
Why we all have a stake in Trump 2.0
Trump's inauguration brings a reset in European politics
Trump likened to 'wrecking ball' for climate action
He will use both a family Bible and the one used by President Abraham Lincoln at his 1861 inauguration as Chief Justice John Roberts administers his oath.
Mr Trump will then deliver his inaugural address, which is expected to last just over 30 minutes and will likely be watched by millions of people across the world.
Former presidents Barack Obama, Bill Clinton and George W Bush will be in attendance, in keeping with former incumbents of the White House attending inauguration day.
However, there will be two notable absences: former first lady Michelle Obama and former House Speaker Nancy Pelosi.
Neither gave an explanation as to why they were skipping the ceremony.
A cadre of billionaires and tech titans who have sought to curry favour with Mr Trump and have donated handsomely to his inaugural festivities, including Elon Musk, Mark Zuckerberg and Jeff Bezos, will also be in attendance.
Following Mr Trump's inaugural address, there will be a ceremonial farewell to Mr Biden and Ms Harris at 12.40pm local time (5.40pm UK time).
Mr Trump and Mr Vance will head to the President's Room just off the Senate Chamber in the US Capitol for a signing ceremony watched by members of Congress at around 12.50pm local time (5.50pm UK time).
An hour later the new president and vice president will attend a luncheon at Statuary Hall in the US Capitol hosted by the Joint Congressional Committee on Inaugural Ceremonies.
Mr Obama, Mr Clinton and Mr Bush will not attend the luncheon despite receiving invites, Sky News' US partner network NBC News has reported.
At around 3.50pm local time (8.50pm UK time), Mr Trump and the new first lady will travel to the Capitol One Arena for the parade celebrations to start.
The original plan for a traditional parade down Pennsylvania Avenue has been turned into an indoor event because of the cold.
Mr Trump will speak to his gathered supporters at the arena, where many of the people who had planned to watch the swearing-in ceremony outside will have watched a live broadcast of the inauguration instead.
The event is expected to feature remarks from Mr Trump and marching bands.
The new president will then head to the White House for an Oval Office signing ceremony at 5pm local time (10pm UK time).
? Follow Trump 100 on your podcast app ?
A trio of glitzy balls will follow in the evening, punctuated by musical performances and remarks from Mr Trump.
Country music band Rascal Flatts and country singer Parker McCollum will perform at the Commander in Chief Inaugural Ball, which is geared toward military service members.
Meanwhile, the US rapper Nelly and disco band The Village People are scheduled to appear at the Liberty Inaugural Ball which is geared towards Mr Trump's supporters.
Singer-songwriter Gavin DeGraw will perform at the Starlight Ball, at which guests are expected to be big donors of the incoming president.
Mr Trump's return to the White House marks a stunning comeback after he overcame criminal indictments and two assassination attempts to regain the presidency.
It also comes after he lost the 2020 election, before denying his defeat and attempting to cling on to power.
He directed his supporters to march on the Capitol while legislators were certifying the election results, sparking a riot that interrupted the country's traditional peaceful transfer of power.
(c) Sky News 2025: Donald Trump to be sworn in as president