The Baths of Titus were public baths (Thermae) built in Rome in 81 by Emperor Titus. The baths sat in the base of the Esquiline hill, an area of parkland and luxury estates which had been taken over by Nero (54–68) for his Golden House or Domus Aurea. Thermae Titi or Titus' baths were built in haste, possibly by converting an existing or partly built bathing complex belonging to the reviled Domus Aurea. They were not particularly extensive, and the much larger Baths of Trajan were built immediately adjacent to them at the start of the next century.
One of the features of the baths was mural designs by the artist Famullus (or Fabullus), both al fresco and al stucco. Before the designs fell into disrepair from exposure to the elements, Nicholas Ponce copied and reproduced them as engravings in his volume "Desription des bains de Titus" (Paris, 1786). The designs are now recognized as a source of the style known as "grotesque" (meaning "like a small cave, a hollow, a grotto") because the ruins of the Baths of Titus were in a hollow in the ground when they were discovered.
A good description of the context in which the baths were constructed and then overbuilt can be found in the Yale Open video lectures by Diana E.E. Kleiner. Lecture 12 includes a discussion of the Baths of Titus.
Lecture 12 - The Creation of an Icon: The Colosseum and Contemporary Architecture in Rome as author at YALE HSAR 252 - Roman Architecture with Professor Diana E. E. Kleiner,
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