The weather-worn sculptor is thought to be one of the earliest depictions of Augustus, who ruled Rome between 21 BC and AD 14.
It was stolen from the Civic Museum of Nepi, Lazio, in the early 1970s and had spent most of the intervening years on display at a museum in Belgium.
Although it was stolen almost five decades ago, museum staff in Nepi had no idea Augustus's head was missing until they carried out a recent inventory check.
Once they realized, alarmed archaeologists immediately began searching for the stolen artefact, and soon found it on display at the Royal Museum of Art and History in Brussels.
The museum had purchased the head from a private dealer based in Zurich in 1975 and ever since it had been sitting in their portrait gallery.
Brussels curators had no idea the item was stolen, as it had never been reported missing by museum staff in Nepi.
As soon as the museum discovered the head's provenance, they quickly agreed to return it to its rightful place and it was presented to the Mayor of Nepi in a ceremony at the Italian Foreign Ministry on Tuesday.
“This is a symbol of the close collaboration between our two countries,” Vice Foreign Minister Mario Giro told reporters.
“It's also a powerful symbol of an inclusive and multicultural Europe at a time when we are seeing cultural genocide and art destruction in countries like Iraq and Syria.”