Best concert you have been to.
For me it was a concert in Fort Collins, Colorado in the summer of 1975 at the football stadium of Colorado State University. Attendance was 40,000 to 50,000 people.
My friends and I sat on the football field in front of the stage and saw Chicago, The Beach Boys and Elton John play for hours and hours. Chicago played first. The Beach Boys played second. Elton John arrived in the stadium via helicopter and took the stage next as a surprise performer. Then all three took the stage and performed together, playing hit songs of all three one after the other. They put on a heck of a show.