Oh Pasadena Rose Palace.
The Chambers Brothers, Brian Auger and Trinity, Elvin Bishop Blues Band & Led Zepplin (touring their first album).
Open stage, no curtains, no "back stage". Open floor seating.
My buddy and I got right up to the stage for the whole show.
Best part of that concert & lineup: all four bands played one set, and then came back for the same rotation and did a completely different set. Zep debuted several numbers from their (not yet released) 2nd album. Most memorable was Heartbreaker and Moby Dick.
In between the two sets Robert Plant came down to the front of the stage and a very polite with two 15.5 year old fans (me and my buddy Dave).