My second concert ever and it remains my fave to this day: The Doors at Boston Arena, April 10, 1970. Thank God for Youtube.
And that's saying something as I also saw Jethro Tull many times in the early and mid-70s including the Aqualung, Thick as a Brick and Passion Play shows, Bowie as Ziggy Stardust, Black Sabbath's first American tour, Pink Floyd's quad Dark Side of the Moon show, Dylan's '74 tour with the Band, Queen's first American tour, Elton's Goodbye Yellow Brick Road tour, etc.
Like some of you guys, I was also a big Uriah Heep fan and saw their Wonderwall show as well as the Demons and Wizards and Sweet Freedom tours. Also saw them way back when they were still unknown in the states when they opened for Three Dog Night in 1970. My favorite Heep album is Salisbury.
Regrettably never saw the Beatles. My parents thought I was too young to go to a concert at that time. But they let me go one year after the Beatles' last tour to see the Monkees at Boston Garden in 1967!
The Doors Boston Arena 1970 - YouTube