BBC News, Rome
 |  One wall is painted with a trompe l’oeil of a theatre  |
The single fragment of painted plaster, discovered in masonry-filled rooms, led the experts to unearth a series of exquisite frescoes commissioned by the man who would later become Rome's first emperor.
On Sunday following decades of painstaking restoration, the frescoes in vivid shades of blue, red and ochre went on public show for the first time since they were painted in about 30BC.
One large room boasts a theatrical theme, its walls painted to resemble a stage with narrow side-doors.
High on the wall a comic mask peers through a small window.
Other trompe l'oeil designs include an elegant garden vista, yellow columns and even a meticulously sketched blackbird.
Builders' names preserved
The Rome authorities have spent nearly 2m euros preserving the four Augustus rooms - thought to comprise a dining-room, bedroom, an expansive reception hall at ground-level and a small study on the first floor.
 The quality of the work has been compared with that in Pompeii |
Archaeologists believe they may have been painted by an Egyptian.
In the large entrance hall, graffiti on one wall is believed to have been left by the builders, who seem to have sketched out geometric designs, possibly for mosaic floors, and left their names.
In 31BC Augustus - or Octavian, as he was then known - had triumphed over the combined forces of Mark Antony and the Egyptian queen Cleopatra at the Battle of Actium.
The victory brought Egypt, and with it immense wealth, into the empire.
But if the frescoes on the walls are exquisite, their surroundings, though impressive, with vaulted ceilings, are less than palatial.
The Roman historian Suetonius described how Augustus lived in a modest house on the Palatine before he assumed supreme power and built a sprawling imperial complex higher up the hill.
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