Initially I read that as “you can go back in time for 24 hours” and thought why would 24 hours ago be that interesting? :)
So my initial answer is: Not eating the late night burger I had last night.
My final answer is: San Francisco in the 60s/70s to hang out with the Dead and all the other amazing artists of that time. Maybe see a show at the Fillmore.
Maggot Brain by Funkadelic is life altering