The Vatican on Wednesday returned a precious fragment of the Parthenon frieze to Greece, prompting Culture Minister Michalis Liapis to urge other nations to follow its example.
''This gesture by one of the most important museums in Europe should be followed by other museums so that the Parthenon marbles can finally be reassembled,'' said Liapis at a ceremony in Athens.
The Vatican Museum also owns two other fragments of the frieze, one of which will be returned next year, Greek news agency ANA-MPA said.
Greece's top religious leader Christodoulos asked for the return of the fragments during a meeting with Pope Benedict XVI in December 2006.
According to press reports at the time, the pope appeared a little startled by the request from Christodoulos, who is the Orthodox Archbishop of Athens and all of Greece.
Benedict nonetheless said he would consider the matter.
Last month, Italy sent Athens another portion of the frieze. The fragment, which the Salinas Archaeological Museum in Palermo has loaned to Athens until the end of the year, had been at the centre of talks between Italian and Greek authorities for years.
It was originally scheduled to return as a long-term loan in exchange for an Italian artefact in 2003 but the agreement fell by the wayside after squabbles over its safe transport.
The fragment was once part of the left side of the sculpted Parthenon frieze from the temple of Athena, which was stripped of much of its decoration during the 19th century.
While the majority of it was carted off to London by Lord Thomas Bruce Elgin, who was serving as British Ambassador in Greece, this particular fragment ended up in a Palermo museum in the 1800s after being purchased from the widow of the British Consul for Sicily, Robert Fagan.
Greece has been calling for the return of the Parthenon marbles since 1981 but with minimal success.
Surviving sculptures are currently located in ten museums in eight different countries, including the Louvre in Paris, but the bulk of them remain in London's British Museum and are known as the Elgin Marbles.
Greece's efforts to get them back and Britain's refusal to let them go have spawned one of the longest-running cultural disputes ever.
Athens argues that the marbles were stolen by Lord Elgin who in 1801 had them chiselled off the Parthenon.
Britain instead says Lord Elgin had permission from the ruling Turkish authorities to take the marbles.
The British Museum also insists the marbles are in better care in London, away from the Athens pollution that has damaged those left behind.
Greece discounts this argument, saying that the marbles will be safe in a new, purpose-built museum which is close to completion and lies within sight of the ruined temple.
The Parthenon - the epitome of the Golden Age of Athens - was originally decorated with a 160-metre-long frieze showing in detail the men, women, horses and sacrificial animals that took part in the annual Panathenaic procession.
By 1800, only 50% of the decoration remained and Elgin took about half of this from the structure and the fallen ruins surrounding it.
Greece says the sculptures are part of its national heritage and that the return of all surviving marbles would allow the restoration of one of the world's greatest artworks.