Nottingham city centre has been bathed in blue to celebrate the birth of the royal baby to The Duke and Duchess of Cambridge.
The young prince and parents are tonight spending their first night at home at Kensington Palace.
More than 18,000 people a minute tweeted about the royal baby as he made his first public appearance this evening, Twitter said.
The figure was short of peak of 25,300 tweets per minute which mentioned the baby last night after the birth was announced.
The easel which held the announcement of the birth of the Duke and Duchess of Cambridge's first child has been removed from the forecourt of Buckingham Palace.
Hundreds of people have been queuing outside Buckingham Palace to see the easel displaying the details of the royal baby. The atmosphere remains jubilant, with many tourists saying they were delighted to be a part of such a momentous day in British history.
The birth of the Duke and Duchess of Cambridge's baby son represents a happy day for the whole country, the Leader of the House of Lords, Lord Hill of Oareford, has said.
The bells of Westminster Abbey sounded out in celebration of the royal birth.
Three of the bell ringers performing the task did the same for the new Prince's father more than 30 years ago.
When the Duke of Cambridge was born in June 1982, Clarke Walters helped ring a peal at the gothic church in central London in honour of the newest member of the royal family.
Mr Walters said it was "wonderful" to now be performing the peal for William's own baby son.
He also rang the celebratory bells for the Duke and Duchess of Cambridge's wedding at the Abbey two years ago.
A team of 10 from the Westminster Abbey Company of Ringers began ringing a full peal on the Abbey's 10 bells at 2pm to coincide with a gun salute in Green Park.
The complex peal is made of 5,000 thousand changes and known as the Cambridge Surprise Royal and lasts for over three hours.
The first glimpse of the future King will make the front pages of newspapers around the world.
Royal photographer Arthur Edwards will be one of the many outside the Lindo Wing of St. Mary's Hospital to capture that moment.
Mr Edwards was there to snap Prince William when he emerged in his father's arms in June 1982.
ITV News' Paul Davies reports:
Gun salutes have sounded across central London today to mark the birth of the Prince of Cambridge.
A 62-gun salute took place from Gun Wharf at the Tower of London.
Meanwhile, the King's Troop Royal Horse Artillery, fired 41 shots from six WWI-era 13-pounder field guns at Green Park.