Park

This is possibly Golden Gate Park, but it was never stated. It may also be different parks around San Francisco.

Innocents Lost
Phoebe and Mika come there to complete a publicity stunt dreamed up by Elise. The publicity stunt has brought many couples to the park to be married by "Ask Phoebe", including a very insistant couple. Coop comes to give Phoebe some reasurance and identifies the couple as Romeo and Juliet. Though Phoebe doesn't originally like the idea, she decides to go ahead with it and marry the various couples gathered there after Romeo and Juliet talk her into it.

Cupid's Harrow
Phoebe and Coop take PJ to the park where they have a picnic. Patty finds Cole watching them and tells him that he needs to get back on track and start really looking for Prue.

Family Shatters
When Piper's powers go crazy and first San Francisco and then the rest of the California stops moving, there is an image of demons coming out to play in the park while children play.