US President Donald Trump will make a state visit to the UK in June.
The visit was announced by Buckingham Palace in April, but it had been a long time in the planning.
He will be staying here for three days in total and will be greeted at Buckingham Palace gardens as part of a special ceremony for visiting US Presidents.
During his stay he will meet many members of the royal family including the Queen, the Duke and Duchess of Cornwall and the Duke and Duchess of Cambridge and the Duke of Sussex.
There will also be a meeting with Prime Minister Theresa May before she steps down from her position on 7 June.
The White House has said the upcoming trip would reaffirm the "steadfast and special relationship between the United States and the United Kingdom".
Prime Minister Theresa May said June's state visit was an "opportunity to strengthen our already close relationship in areas such as trade, investment, security and defence, and to discuss how we can build on these ties in the years ahead".
Here's everything that you need to know about Mr Trump's UK trip.
US President Donald Trump's state visit is due to take place between Monday 3 and Wednesday 5 June 2019.
He will be joined by his wife Melania.
We know that Mr Trump and his wife will be guests of the Queen to attend a ceremony on 5 June in Portsmouth to mark 75 years since the D-Day landings.
After leaving the UK, Mr Trump and Melania will head to France for D-Day anniversary events on 6 June.
We also know that he will be meeting with the prime minister at Downing Street. It is quite traditional for state visits to include meetings between the visitor and the prime minister, government ministers and leaders of the main political parties
A visit to - and speeches at - the Houses of Parliament can also be on the itinerary.
A spokeswoman for Commons Speaker John Bercow has said previously that a request for Mr Trump to speak to politicians in this way would be "considered in the usual way" and did not confirm if such a request had been made yet.
Mr Bercow has the power to refuse to allow such a speech to happen in the House of Commons. He has previously said he would be "strongly opposed" to Mr Trump addressing the Commons.
Foreign Secretary Jeremy Hunt, an important government minister, has said that he thinks that Mr Trump should address MPs during his trip.
While details of the president's trip are being finalised, there are some traditional elements to a state visit which we could expect might happen.
Usually the Queen and other members of the royal family greet the visitors with a ceremonial welcome. This takes place on Horse Guards Parade and involves a carriage procession escorted by mounted soldiers.
There are also gun salutes fired from Green Park and the Tower of London.
There is also normally a state banquet, which is a very big formal meal held in the ballroom at Buckingham Palace.
Around 150 guests are invited, with the Queen making a speech and proposing a toast to the visiting head of state.
State visit guests usually stay at Buckingham Palace or Windsor Castle.
BBC royal correspondent Jonny Dymond explains that a key part of a state visit is a procession down the Mall in front of Buckingham Palace.
But Mr Trump avoided London on his trip to the UK in 2018 making it clear that he did not want to come to the capital if he would be faced with protests, which could happen at a Mall procession.
People have different opinions about Mr Trump visiting the UK and the fact that he has been invited for a more formal state visit.
Prime Minister Theresa May has said it is a chance for the US and UK "to strengthen our already close relationship".
But others don't think that he should be given such a formal and important welcome.
Some UK politicians, including Labour leader Jeremy Corbyn, have already said they won't attend the special banquet in honour of the president.
Protests are expected to take place in London when he comes, with anti-Trump campaigners planning on flying a controversial balloon - which shows Donald Trump as a baby holding a mobile phone - in the skies over London.
This happened last time he visited in July 2018, when demonstrations also took place.
When Mrs May first invited Mr Trump for the state visit on behalf of the Queen back in 2017, it proved quite controversial because when the idea was first suggested, over 1.8 million people signed a petition calling for it not to go ahead.
People were angry after he did come for his working visit in 2018 because it was estimated that the police operation for it cost nearly £18 million. Nearly 10,000 officers from across the country were needed to provide extra security throughout the US president's four-day trip.
In February 2019, it was reported that Thames Valley, Essex and the Metropolitan forces were repaid a total of £7.9m by the government for hosting the president.