In 2002, the Italian Government announced that they were going to return a fragment of the Parthenon frieze back to Greece. Since then, due to arguments between the museum in Palermo (which currently holds the piece) & the Italian government, the piece has still not been returned.

From:
[1] Kathimerinini English Edition

Monday May 17, 2004
Papal blessings for Olympics organizers

VATICAN CITY (AP) - Pope John Paul II urged on Saturday that the forthcoming Olympics should be a show of fraternity and peace, and offered his blessings to the organizers.

He was speaking at a meeting with Athens Mayor Dora Bakoyannis, who is on a European and US tour ahead of the Games. “I express the wish that the next celebration of the Olympic Games in your city be a show of brotherhood for all the participants and a message of peace and union for all those who will be spectators across the world,” John Paul said. “In this spirit, I invoke divine blessings for you and all the organizers of this celebration.”

In a meeting earlier on Saturday with Italian Culture Minister Giuliano Urbani, Bakoyannis raised the question of the long-term loan to Greece of a small piece from the 5th century BC Parthenon frieze displayed in a Palermo museum. Agreed in late 2002, the loan has yet to materialize.