1981, Pontiac Silverdome (with it’s giant balloon of a roof).
Iggy Pop / Santana / Rolling Stones
Santana blew the roof off the place and actually managed to sound good, in that stadium. I’ve seen Santana literally dozens of times since about 1980 and he has always had some of the best live sound of any "rock" show I’ve seen. But managing to pull it off in the notoriously awful-sounding Silverdome (saw the Who there about a year prior, and the lyrics were absolutely unintelligible from start to finish) was a live sound engineering marvel, IMO.
Not only that, but he really blew the Stones off the stage as well. Their performance was moderately average to mediocre in both sound and execution. Word was that they almost had to pull Santana off the stage after their 90-minute set, they were so smoking. Probably the best Santana show I’ve ever seen (next to the one I took my then 3-year old daughter to, which amazingly enough, turned HER into a lifelong Santana fan, even to this day; she was at the recent show at Pine Knob when he collapsed onstage from heat exhaustion).