Dont know if this counts.
My first free party experience was at Inukshuk at the Sanctuary in Birmingham, November 2003 Even though it was in a club it was still free.
The main room was Techno (it always is), I had never danced to Techno before, I loved it.
Everyone was so friendly I made a lot of friends whom I still see.
It just had a lovely feel to it, no trouble, no nasty people, just fun and friendly.
I have only ever missed one since, and thats when I was pregnant.