Archaeologists have unearthed what they say are the only existing imperial insignia belonging to Emperor Maxentius — precious objects that were buried to preserve them and keep them from enemies when he was defeated by his rival Constantine.

Excavation under Rome's Palatine Hill near the Colosseum turned up items including three lances and four javelins that experts said are striking for their completeness — digs usually turn up only fragments — and the fact that they are the only known artifacts of their kind.

Some of the objects, which accompanied the emperor during his public appearances, are believed to be the base for the emperor's standards — rectangular or triangular flags, officials said.

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An imperial scepter with a carved flower and a globe, and a number of glass spheres, believed to be a symbolic representation of the earth, also were discovered.

The discovery was announced Wednesday by Italy's Culture Minister, Francesco Rutelli, during a visit to New York.

The items, inside wooden boxes and wrapped in linen and silk, were found buried at a sanctuary last year and have since been restored and analyzed. The depth of the burial allows experts to date them to the early 4th century A.D., ministry officials said.

"These artifacts clearly belonged to the emperor, especially the scepter, which is very elaborated, it's not an item you would let someone else have," Clementina Panella, the archaeologist who made the discovery, said Friday.

"As far as we know, there are no similar findings," said Angelo Bottini, the state's top official for archaeology in Rome. "Similar representations are only on coins and paintings, but we never saw them for real," he said. Bottini added that the artifacts will be shown to the public in February.

Panella said the insignia were likely hidden by Maxentius' people in an attempt to preserve the emperor's memory after he was defeated by Constantine I in the 321 A.D. battle of the Milvian Bridge — a turning point for the history of the Roman empire which saw Constantine become the unchallenged ruler of the West.

"Once he's lost, his objects could not continue to exist and, at the same time, could not fall in the hands of the enemy," she said.

Darius A. Arya, an archaeologist and professor at the American Institute for Roman Culture, said the discovery was highly unusual.

"Here's something precious that represents the greatness of Maxentius, buried by his loyal people to save something that belonged to him," said Arya, who was not involved in the excavation. "All together, they represented the power of this particular emperor and you wouldn't want the enemy or the usurper to get a hold of it."

Excavations on the Palatine in recent decades have turned up wonders such as the house of Rome's first emperor, Augustus. Experts said that much has yet to be uncovered, hidden in underground passageways.