Atomic Cafe

Between 1989 and 1992, the Cacophony Society held 3 legendary events known as "The Atomic Cafe". These were major urban infiltration takeovers of abandoned underground concrete structures in the San Francisco area.
en.wikipedia.org/wiki/Urban_exploration

The October 1998 Cacophony event calendar listed this event description: "AN EVENING AT THE ATOMIC CAFE - The end has come. You and a handful of glowing degenerates have huddled together at the Atomic Cafe. Join the last remnants of society as we leave the nuclear wasteland and, under the cloak of darkness, descend into an underground chamber. Bring food and drink with a shelf life (canned goods such as fruit cocktail are highly recommended), your personal mementos from your destroyed past and precious articles to barter in your apocalyptic future. Dress in appropriate radiation mode."

Atomic Cafe #1 was held on the night of Oct 7, 1989 in a WWII military bunker overlooking the ocean near the Golden Gate Bridge. 25 participants were blindfolded at a nearby location, led to the bunker and then climbed down a rusty metal ladder into the underground chamber, which had been painted with scenes of apocalyptic destruction by a group of students from the San Francisco Art Institute. The decorated chamber was furnished with 3 cloth-covered cafe tables, chairs, a portable toilet, and a power inverter which ran a 16mm projector showing duck & cover training films and nuclear explosions. A secret latch was installed on the other side of a trap door, which allowed this location to be used many times by the Cacophony Society over the next 4 months before it was finally discovered and sealed by the US Park Service.

Atomic Cafe #2 - was held on the night of June 2, 1990 in the basement of a 4-story GSA building located south of Market, which had been abandoned for 14 years. 70 participants met at a bar were they were then loaded into the back of a 24' rental truck and then driven in circles for a few blocks. Organizers with radios and rooftop lookouts co-ordinated the raising of a large rollup door and timed the arrival and entry of the truck, which drove down a ramp to the basement of the building. The participants were led though a maze of decaying rooms and finally to a large set of double doors, which were opened to reveal a live band, light show and fog machine. Power was provided by a generator, which had its exhaust pipe connected to restroom vent plumbing in order to exhaust the fumes to the roof, 4 stories above. At the end of the party, participants were loaded back into the truck and driven out without ever revealing the location of the event.

Atomic Cafe #3 - was held on the night of Feb 8, 1992 in the basement of a sprawling toothpaste factory complex in Berkeley. 130 participants met a nearby bar, were they were loaded into a rental truck, which was then driven down an abandoned railroad track to the back of the block-long factory. Participants crawled under a fence and then were led to a hole in the ground, which revealed a large multi-room underground basement filled with rusting machinery and pipes. Couches and other furniture had been hauled into an open area in the basement complex, where a potluck dinner party was held. After a speech by Larry Harvey, a giant bomb was lowered into the assembled group. The bomb was a pinata filled with toy soldiers and war toys.