The School of Athens
Movement: Renaissance
If you want one picture that sums up the Renaissance, this fresco in the Vatican is it. Raphael painted it around 1509 to 1511 for Pope Julius II, and it gathers the philosophers of ancient Greece under grand classical arches, with Plato and Aristotle at the center. Everything the period cared about is here at once: revived ancient learning, believable people with weight and gesture, and a deep, orderly space built with linear perspective so the eye runs straight to the two central figures.
What came next: younger artists, having seen this kind of perfection, started bending the rules on purpose.
More about The School of Athens