Representation of the kosmos is one of the leading themes of Roman decoration. If the evidence for public interest in cosmic representation is generally well known – for instance, at the Pantheon at Rome – it is worth noting that this phenomenon has not been sufficiently studied in the realm of private life. This piece investigates several examples of cosmic architecture and images known through written texts or archaeological monuments, all of them belonging either to aristocratic houses or to imperial palaces: the aviary that M. Terentius Varro built around 80 BCE inside his villa at Casinum; the Teatro Marittimo that the emperor Hadrian erected at his villa in Tivoli (early or mid-second century CE); the the cave of Sperlonga, which formed part of Tiberius’s Praetorium; and the Cenatio Rotunda, which belonged to Nero’s Domus Aurea. Kosmos-representations in the private sphere at Rome are arranged according to the particular point of view of the persons who frequent the place where they are located. Chief inspiration for these decorations would appear to have been the philosophers, especially Plato, but also the Greek astronomers, who fascinated the Roman elite, as demonstrated by the Latin translations of the Phaenomena of Aratus by Cicero and Germanicus.