A year before Simon & Garfunkel did, Elton John took the stage at Central Park's Great Lawn and played for around 400,000 people. The show was free, took place on September 13th of 1980, and it was recorded for a TV special... so there's some great footage of it available. Check out some of his hits below:

"Rocket Man"

"Bennie & The Jets"

"Imagine" — Elton John addresses the audience, saying this song was written by "a friend of mine who I haven't seen for a long time, but... he only lives just over the road. He hasn't make a record for ages, but he's doing well at the moment." John Lennon was murdered less than three months later.

"Tiny Dancer"

"Your Song"

And here's some "rare footage" from a news report on the concert (unfortunately not in English, but it includes great fan shots):