The School of Athens by Raffaello is perhaps the single most iconic image of the High Renaissance that is also the cover of Use Your Illusion I and II.
Coincidentally, the Renaissance was also when Chinese Democracy was first announced.
The Easter Egg:
While we could spend all day talking about the cameos Raphael slipped into the fresco ...
That's Socrates, all four of the ninja turtles and many, many others. It's like the Ocean's 11 of paintings.
... they're nothing compared to the Easter Egg Renaissance master Donato Bramante contributed to the project. According to Giorgio Vasari's Lives of the Most Excellent Painters, Sculptors, and Architects, Raphael had Bramante design "the architecture" for the fresco and, sure enough, Bramante's contribution was a carbon copy of the floor plans for the new St. Peter's Basilica he was working on just down the street. The School of Athens wound up offering a ground-level glimpse at the completed work more than a century before it would be finished.
It's a nice enough church, but the glare will literally melt your corneas.