Here’s one in Portland OR, known locally as pirate town.
It was first an industrial site on the Willamette river that provided saws for the lumber industry. ( Simonds?) , then became part of a creosote plant that of course became a superfund site. The place was purchased by a University next door and torn down as part of the remediation and will become soccer fields and a rowing boat house, but for a decade or so it was a counterculture skateboarding haven. All the ramps and such were built by kids.
pirate town eulogy
Pirate Town
Of course it couldn’t stay, but it was cool while it existed.