Tens of thousands of pro-EU demonstrators have taken to the street of London, despite heightened concerns about the terrorism threat, to mark the European Union's 60th anniversary -- just days before Britain's exit from the EU is expected to formally begin.
Organizers said about 80,000 people joined the march calling for Britain to stay in the EU on March 25.
The demonstration came four days before British Prime Minister Theresa May said she would formally start Britain's exit negotiations by invoking Article 50 of the EU's Lisbon Treaty.
Hundreds of blue EU flags were carried by protesters in the procession as it stretched through central London.
Banners carried by the demonstrators had slogans like "I am European," and "I'm 15 -- I want my future back!"
The protesters fell silent as they moved through Parliament Square, where a British-born terrorist earlier this week drove a car through crowds of people before crashing into a fence and stabbing a police officer to death.
One banner raised in front of Britain's Parliament said, "Terrorism won't divide us -- Brexit will."
Another said, "Stop sleepwalking, stop this madness."
About 10,000 EU supporters also marched in Rome on March 25 while about 4,000 gathered in Berlin.