Greece's largest museum, the National Archaeological Museum in Athens, one of the most important of its kind in the world, will undergo a massive upgrade expected to last four years, officials said Wednesday.

Inaugurated in 1889, the museum houses some of the country's most valuable antiquities.

The Bronze Age gold treasures of Mycenae, the prehistoric frescoes of Thera, and the 2nd-century BC Antikythera Mechanism, a device believed to be the oldest computer in the world, are just three antiquities of many others in the 150-year-old museum.

An international architectural competition was concluded in December to expand the capacity of the museum that attracts more than 500,000 visitors every year.  

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The plan by David Chipperfield Architects and Greek partners Tombazis involves two new levels of subterranean galleries with a raised roof garden, structured to create 20,000 square meters of more space.  

"This museum has one of the most extraordinary collections in the world," Chipperfield told the museum presentation, adding, "We will try to close this building as (little) as we can" for the works.

Culture Minister Lina Mendoni said the museum would be "completely" transformed in four years; however, she did not provide specific details on the completion date.

Less than a tenth of the several thousands of items in the museum's collection are currently on display, Prime Minister Kyriakos Mitsotakis said, adding that national and EU resources will be funding the project.

Chipperfield has worked in the Museo Jumex in Mexico City, the Neues Museum in Berlin, and the Saint Louis Art Museum in Missouri.

The last project of this kind in Greece was in 2009 when French-Swiss architect Bernard Tschumi worked on sprawling the New Acropolis Museum, which drew over 1.7 million visitors annually before the coronavirus pandemic.

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