When a young Roman inadvertently fell through a cleft in the Esquiline hillside at the end of the 15th century, he found himself in a strange cave or grotto filled with painted figures. Soon the young artists of Rome were having themselves let down on boards knotted to ropes to see for themselves. The Fourth Style frescoes that were uncovered then have faded to pale gray stains on the plaster now, but the effect of these freshly rediscovered "Grotesque" decorations was electrifying in the early Renaissance, which was just arriving in Rome.