Twenty-five years of archaeological finds will go on show in Rome from Saturday, showcasing priceless ancient artefacts and curious pieces of cultural history mostly uncovered by preservational digs before building works.

"Underground memoires" will highlight the luxurious life of Roman emperors with perfume bottles, game pieces, jewellery, a bronze soap holder and coins.

Unusual finds uncovered by the archaeologists included a cache of passionate love letters from the 1920s found in a lead cylinder under the Appia Antica Roman road, used today by ramblers.

The exhibition in the "Olearie Papale", the public granaries within the ruins of the Baths of Diocletian, aims to show the public that "the world's largest archaeological museum lies under the city".

"There are 1,500 pieces in their exhibition, but there are three or four times more in the warehouses" said Robert Egidi, an archaeologist who worked on the excavations.

In Rome regulations stipulate that excavations must explore the sites of any construction projects, however small, before building can go ahead.

The archaeological richness of the soil delights fans of Italy's cultural heritage, but poses frequent problems for developers. "Every time works start, we find something," Egidi told AFP.

Rome's third metro line is a testament to these obstacles, waiting years for the archaeologists to give the all clear.