celebration of marijuana becoming legal in Colorado

It started years ago as a rally to generate support for the legalization of marijuana.

So after Colorado passed officiated laws for recreational marijuana on January 1, this year's 4/20 was always going to be monumental.

Some 80,000 people flocked to Denver's Civic Park on Saturday for the first of the two-day event, making it the world's largest cannabis culture music festival.

Organizers invested in a major security increase for the free outing.

Police reported a relatively low 25 arrests for Saturday, with pot smoking only legal on private property, according to ABC Denver.

While last year's festival turned out record numbers, they were expected to double this year.

Police said 17 of the citations handed out were for public consumption, five were for DETOX and two were medical calls.

At least four of the citations went to out of state residents.

One person was transported to the hospital from the rally, but authorities have not released further details.

The entire festival area was fenced in with controlled entry points.

Those attending were patted down and no bags were permitted inside the festival area.

Among the rules posted at entry points was one that stated it is illegal to consume marijuana at the event.

Although recreational marijuana is legal in Colorado, it is illegal to smoke it in public.

Traditionally, all attendees light up at 4.20pm.

Organizers made it clear on their website that they 'discouraged' such behavior.

Civic Center Park is a public park located between the state capitol and the Denver City & County Building.