Skate parks are good 3rd places.

Unlike other hobbies or sports, you don't necessarily need to be a member of a club, get expensive equipment or be on a specific time.

Lots of young people just hang out. There's a large overlap with various subcultures. If there's a group of skaters, they'll usually have a whole entourage of photographers, artists and musicians.

Sometimes it's a little too succesful though. Some skate parks are build in isolated areas, which can attract all kinds of scum. Then it's best to come when actual skaters are using it.

It's usually very inclusive. Nobody cares about age, gender, race or abilities. Skaters respect anyone who goes out there and tries. This is also why random scum will usually fuck off when they realize that nobody gives them attention for reving up their moped engines or whatever they do to piss off their territory.