Woodstock
Woodstock was a music festival that took place in 1969. (COMIC: A Little Help from my Friends)
The Twelfth Doctor told Clara that his tambourine solo was one of the highlights of Woodstock. (PROSE: The Crawling Terror)
Woodstock was among the things the Eleventh Doctor associated with the "swinging sixties". (AUDIO: Hunters of Earth)
When on the Twist, the Twelfth Doctor mentioned Woodstock while talking about open-air concerts. (COMIC: The Twist)
The Seventh Doctor once speculated that there would be at least two versions of himself at Woodstock. (PROSE:The Left-Handed Hummingbird)
Graham O'Brien was too young to attend the event when it was taking place. The Thirteenth Doctor tried to take Graham, Ryan Sinclair, and Yasmin Khan to the concert, but the TARDIS brought the crew to London in 1969 instead. (COMIC: A Little Help from my Friends)