The U.K. finally leaves the EU — nearly 4 years after Brexit vote

Britain has left the European Union, becoming the first member state in the bloc's history to do so. In a speech ahead of Brexit, Nigel Farage, one of its primary architects, told a crowd of thousands gathered in London's Parliament Square that "the people have beaten the establishment."

"The war is over. We have won," Farage said. "This is the greatest moment in the modern history of our great nation."

The United States' ambassador to the U.K. wished Britain "every success" ahead of Brexit.

"America shares your optimism about the many opportunities the future will bring," Woody Johnson tweeted, saying Brexit had been "long supported" by U.S. President Donald Trump.

One young Brexit supporter who was out to celebrate Britain's break with the EU said he was looking forward to possible opportunities for the U.K. to trade with other commonwealth countries and the United States.

19-year-old Zach, who is studying classics at London's Royal Holloway University, said he was excited about trade with the U.S. "if they choose to be nice and behave."

British Prime Minister Boris Johnson said it was "the dawn of a new era" in a pre-taped video address released an hour before the U.K. was set to officially exit the European Union.

"In our campaigns for human rights or female education or free trade we will rediscover muscles that we have not used for decades. The power of independent thought and action," Johnson said.

He explained that the priority for Britain once outside the EU would be to "no longer accept that your life chances – your family's life chances - should depend on which part of the country you grow up in."

"We have taken back the tools of self-government," he concluded.

"Now is the time to use those tools to unleash the full potential of this brilliant country and to make better the lives of everyone in every corner of our United Kingdom."

A crowd was gathering in Britain's Parliament Square Friday evening to celebrate the U.K.'s departure from the European Union. Hundreds of people were assembled on the muddy grass in front of Westminster as edited historical news clips were played on a large video monitor.

Democratic Congressman Brendan Boyle, who last year introduced a resolution in congress opposing the establishment of a hard border between Northern Ireland and the Republic of Ireland after Brexit, tweeted his thanks to those who made sure that did not happen.

Boyle is the son of Irish immigrants to the United States and had been concerned that a hard border between Ireland and Northern Ireland would threaten the landmark peace agreement that ended years of sectarian violence in the region.

The U.K. flag has been taken down from the European Council and European Parliament buildings in Brussels. Hours ahead of Britain's exit from the European Union, with little fanfare, officials were seen swiftly removing the flags.

Most of the British newspapers had Brexit on their front pages Friday, as the U.K. prepared to leave the European Union. The Daily Mail headline read, "A new dawn for Britain," while the Sun's said, "Our time has come."

The Telegraph's headline read, "This is not the end, but a beginning," and the Guardian's said, "Small island."

There was a campaign by Brexit supporters to raise enough money to get London's iconic Big Ben to ring out Friday in honor of Britain's departure from the EU, but it fell short.  

Brexiteers commissioned their own bell, called "Little Ben," which arrived at Parliament Square on Friday.

Brexit campaigner David Waller told CBS News the bell in the back of his van was cast at the Whitechapel Foundry, the same foundry that created the Liberty Bell in Philadelphia.

"The actual bell is on a Victorian carriage and it's been made by a very able blacksmith by the name of Merve Smith, who is a second generation blacksmith from sleepy Shropshire," Waller said.

Waller was planning to ring Little Ben, which remained carefully packed and obscured from view as he spoke to CBS News, at the moment of Brexit, 11 p.m. in London, Friday night.

Dozens of pro-Brexit and pro-EU demonstrators exchanged words outside the British Parliament on Friday afternoon. 

Standing on either side of a road and separated by police, one Brexit supporter yelled, "bye bye EU scum," and "now we can be great again." 

A woman draped in a British flag held her hands up in the symbol of the letter L and shouted "losers" at the pro-EU activists across the street.

CBS News partner network BBC News posted video on Friday of the flags coming down at the building Britain has inhabited at European Union headquarters for decades. 

The U.K. Representation to the EU was effectively the kingdom's embassy in Brussels. The BBC News clip showed the moment on Friday afternoon when the two flags — A Union Jack and the EU circle of stars on blue, were brought in through a window.

Around 100 people gathered outside Europe House on Friday to say goodbye to officials at the home of the European Commission in London. 

Some people were in tears as the crowd, many of them waving EU flags, listened to speeches of thanks from officials exiting the building.

"I am old enough to remember us going into the EU, and I don't think that at that stage I was keen on the idea… But my life has involved Europe to varying degrees," one demonstrator, John Minson, told CBS News. "It just led to a growing realization that, well, I knew people were all the same, but that we can all stand together. That the language barriers don't matter. That geographical barriers don't matter. That if we have the same interests, we can work together and make interesting things happen within the world."