Designed by the architects Severus and Celer and decorated by the painter Fabullus, the palace consisted of a series of buildings separated by gardens, woods and vineyards, and an artificial lake in the valley where the Colosseum stands today. The main cores of the palace were located on the Palatine and Opium Hills and were famous for their lavish decoration, in which stucco, paintings, and colored marble were complemented by gold and precious stones. The vast complex included baths with normal and sulphuric water, several banquet halls, including the famous rotunda of the Coenatio that turned on itself, and a huge vestibule that housed the colossal statue of the emperor in the guise of the sun god.
After Nero's death, his successors wanted to erase all traces of the emperor and his palace. The luxurious halls were stripped of coverings and sculptures and filled with earth up to the vaults to be used as foundations for other buildings.
The parts that can be visited today are those on the Oppio Hill: rooms that were probably intended for feasts and banquets, which were buried and remained unknown until the Renaissance. It was then, after some accidental discoveries, that artists with a passion for antiquity, such as Pinturicchio, Ghirlandaio, Raphael and Giulio Romano, began to descend from above into these "underground caves" to copy the decorative motifs they had preserved, which, precisely because of their location, were given the name "grotesque".
Even today, the term "grotesque painting" is used to refer to a genre, particularly popular in the 16th century, that takes up the motifs of Roman wall decoration, reworking and reinterpreting them in a playful and imaginative way.