The marble relief, created during the reign of Emperor Hadrian in the second century AD, has been exhibited at the Princeton University Art Museum since 1986.
But museum officials only realised it had been taken from Italy without a legal export permit after stumbling upon a reference to its discovery in an academic work.
The sculpture includes the bust of a bearded man called Aphthonetus and a Latin inscription, and comes from a Roman marble funerary monument.
It was discovered near Tibur, central Italy, in the early 1980s when land was being prepared for ploughing.
It was acquired by the museum from a dealer in 1985 - but the museum did not realise it had been wrongly removed from its place of origin until a museum official found a reference to the discovery in 2000.
'Grateful'
After an unsuccessful search for the owners, the museum decided that returning the sculpture to Italy was the right thing to do.
Italian judge Marshall Angelo Ragusa will meet the museum's director Susan M Taylor to discuss the offer.
Ms Taylor said: "We are grateful to Marshall Ragusa and to the various agencies of the Italian and US governments for their assistance in returning this work to Italy and in righting the wrongs perpetrated prior to its acquisition by this museum 17 years ago."
The museum also recently resolved another ownership dispute after they reached an agreement with the heirs of the owner of a Pinturicchio painting that was sold in Nazi-occupied France in 1941.