For more than 30 years, Greece has been working, through diplomacy and public relations offensives, to regain the Elgin Marbles, sections of a decorative frieze that adorned the Parthenon until Lord Elgin ordered them removed in the early 19th century, during his tenure as British ambassador to the Ottoman Empire. Years later, bankrupt, he sold them to the British Museum, where they have been a major attraction since 1816.  Today, almost two centuries on, many Greeks hope the opening of the museum will focus international attention on their country’s claim to the so-called Elgin Marbles, and put an end to Britain’s longtime argument that it is in a better position to look after those 2,500-year-old panels. Last week the Greek government turned down an offer from the British Museum for a three-month loan of the collection, because it came with the condition that the Greeks formally acknowledge British ownership.  “This is a nonstarter for any discussion,” Mr. Samaras said. “No Greek can sign up to that.”  The new museum, 226,000 square feet of glass and concrete designed by the New York architect Bernard Tschumi, replaces the old Acropolis Museum, a small 1874 building tucked into the rock of the Acropolis next to the Parthenon. The design, introduced in 2001, was meant to be completed in time for the 2004 Olympics, but dozens of legal battles — many having to do with some 25 buildings that were demolished to make room for it — delayed the process for years.  Even now, not all Athenians are happy with the building, wedged in as it is among apartment buildings in a middle-class residential district. “It is as if a titanic U.F.O. landed in the neighborhood, obliterating all of its surrounding structures,” said Nikos Dimou, a prominent Greek author.  The museum has five floors (including two basement levels that will not be open at first), which provide space for 4,000 artifacts, 10 times the number displayed in the old building. On the first level a glass floor offers visitors close-up views of an early Christian settlement, dating from the 7th to 12th centuries, that was discovered under part of the future building’s footprint during excavations in 2002.  The second floor, reached by a glass ramp, features a rich trove of free-standing objects from the archaic and classical periods. But it’s really the third and top floor — a glassy gallery — that Mr. Samaras and other Greeks hope will advance their country’s cause with Britain and the rest of the world.  Rotated 23 degrees off the axis of the lower floors to parallel the Parthenon itself, this rectangular glass enclosure feels dramatically different from the rest of the museum. Like a 21st-century surrogate of the monument looming above, it displays what remains in Greece of the original Parthenon sculptures and frieze, alongside plaster casts of the works in London. The contrast between the glaring whiteness of the copies and the ancient, honey-colored marbles makes for a powerful, and calculated, statement.  “We wanted it this way,” said Dimitris Pandermalis, the museum’s director. “Who will fail to notice that a torso is here and a head in England?”  Greece retains only 36 of the 115 original panels from the Parthenon frieze, which depicts a procession in honor of the goddess Athena. Britain has long asserted that when Lord Elgin chiseled off the sculptures some 200 years ago, he was acting legally, since he had permission from Greece’s Ottoman rulers. That legality, however, has been challenged by Greek scholars in recent years, with the government in Athens spurning it altogether.  “The claim is bogus,” said George Voulgarakis, a former Greek culture minister. “It’s like saying the Nazis were justified in plundering priceless works of art during the Second World War.”  In recent years Greece has tried to build international support for its repatriation campaign by going beyond mere demands, for example joining forces with Italy in 2007 to crack down on antiquities theft and nefarious art dealers who trade in looted works. At least 25 artifacts have lately come back to Greece, including fragments from the Parthenon frieze that were displayed for decades at museums in Italy, Germany and the Vatican.  So far the British Museum trustees have not seemed to be swayed, beyond the offer of the three-month loan.  Late on Friday, about 50 Greek demonstrators marched at the base of the Acropolis to protest the British Museum’s defiance.  “Enough with the excuses,” said Alexis Mantheakis, the protest organizer. “The Parthenon Marbles now have a new Greek home.”  A version of this article appears in print on , on Page C1 of the National edition with the headline: In Athens, Museum Is an Olympian Feat. Order Reprints| Today's Paper|Subscribe
The New Acropolis Museum, one of the highest-profile cultural projects undertaken in Europe in a decade, opens this weekend.