With a state banquet on the agenda and a full ceremonial welcome in the gardens of Buckingham Palace, plenty of interesting items have been laid on for the US president's state visit to Britain.
But Barack Obama and his wife Michelle will particularly have enjoyed meeting the royal family's new golden girl.
And they were probably the envy of everybody back home in America because as the leader told Prince Charles, his whole country was fascinated by the royal wedding.
The first lady finally caught up with Catherine, Duchess of Cambridge for a relaxed 20-minute chat in the lavish 1844 room of Buckingham Palace, along with their husbands.
In a sign that despite the newlyweds' popularity they are not yet full-time working royals, no TV cameras or journalists were allowed.
Her newcomer status didn't prevent Kate - who was chic in a £170 Reiss beige structured dress, which set off her deep tan - handling the meeting with her usual composure and grace.
Now seasoned at negotiating the spotlight, the charismatic American may have been able to give Kate some tips on life in the public eye.
They probably also touched on the royal couple's highly-anticipated trip to Canada and the US in July.
William, fresh from their ten-day honeymoon in the Indian Ocean, was also sporting more colour than usual thanks to the strong Seychelles sun.
He seemed to be deep in conversation with the president, with the two men at ease as they chatted away.
The VIP guests then stepped into the garden for a full ceremonial welcome, which included the playing of both the American and British National Anthem.
And a 41-gun salute from the Tower of London was fired by the Honourable Artillery Company to mark the second state visit by a US President during Her Majesty's reign.
Michelle and the Queen looked on as their husbands inspected the first battalion Scots Guards. Earlier in the day, the monarch and Prince Phillip had greeted the Obamas at the entrance to the Palace.
The leader then traveled to Westminster Abbey to lay a wreath on the Tomb of the Unknown Warrior and sign the visitor's book.
This was followed by a short meeting with David Cameron in Downing Street.