April 20 has been celebrated by cannabis users for decades, with gatherings taking place around the world.
In London, this is the first time that pot smokers can gather legally and observe their counterculture holiday.
A few dozen pot smokers gathered at Victoria Park, the first time on this date they've been able to legally light up.
"I never thought we would see this day," one woman said at the 4-20 event in the park.
During a five-year span from 2011 to 2016, there was a heavy police presence in the park. On Saturday, there was not an officer in sight.
"For a few years there was zero tolerance policy which was sad," cannabis advocate Eric Shepperd said.
"Some years there was more police than protesters... After the Liberal government was elected, they disappeared and now we're just having a nice day at the park."
Shepperd said even though cannabis users have achieved legalization, more can be done.
"It's a cause for celebration. We're seeing the end of a legal regime of prohibition. but there is still refinements to be made and changes to make it more liberalized for the Canadian culture.
At Central Cannabis on Wonderland Road North, there were lineups out the door at one of the two brick and mortar legal pot shops in the city.
Customers were thrilled to be able to purchase product lawfully.
“It’s like Christmas morning. You come down the stairs and see your legal marijuana,” said Mike Lees.
“Because of cannabis users, the governmen't had to figure it out," said Luc Gaffan of Central Cannabis.
“I'm glad they did because we have this situation. The past few weeks we've been open, we’ve had a diverse customer base."
