Treasures filled the “splendid villa” in Lanuvio, south of Rome, which was transformed into “a small private museum”, Italy’s financial police said on Monday.
Roman columns, statues, decorated marble and fragments of mosaic were found along with funeral plates and well-preserved terracotta vases.
In one room police found display cabinets filled with ancient artefacts, while elsewhere they uncovered a bas-relief depicting a hunt and a collection of coins.
The vast haul has been catalogued with the the help of the Lazio region’s cultural heritage superintendency, police said.
Four people have been reported and accused of illegally possessing cultural heritage and state property.
Given Italy’s wealth of ancient sites, the country’s police force is embroiled in a continuous battle with heritage thieves. In March, a gang broke into Pompeii and stole part of a fresco from the UNESCO World Heritage site, despite security being upped in recent months.
Italian authorities also work with their counterparts internationally in order to reclaim ancient treasures which have found their way onto the international market. In March, Switzerland finalized the return of 4,500 artefacts robbed from Italy, completing a process than had begun in 2001.