The museum was decades in the making. In 2000, the Municipality of Athens bid at an auction of Callas's personal effects, assembling a small collection with hopes of an exhibition for the 2004 Olympics. That deadline passed. In 2010, under mayor Nikitas Kaklamanis, the city bought the former Royal Hotel on Mitropoleos Street for seven million euros, intending at first to install a theatre museum there. When that plan collapsed three years later, someone made the obvious connection: here was an empty neoclassical building in the heart of Athens, and there was a Callas collection in search of a home. For the 2023 to 2028 period, the museum was placed under the management of the team behind the Technopolis cultural venue.

Most biographical museums are built on objects. This one was built on sound. The museum's co-designer, architect and museologist Erato Koutsoudaki, was disarmingly frank: the collection, she said, was not the museum's strong card. Instead, the exhibitions are constructed around Callas's personality - and above all around her singing voice and her interviews. You do not simply look at Maria Callas here. You hear her. The result is a portrait assembled from recordings, projection, and atmosphere as much as from glass cases, an attempt to convey what made a voice, rather than a wardrobe, immortal.

The objects that are here, though, carry their own weight. There are operatic costumes - including pieces from her 1960 Norma and 1961 Medea at the ancient theatre of Epidaurus - alongside haute couture garments, some made by the Milanese designer Elvira Leonardi Bouyeure, known simply as Biki, who dressed Callas off the stage. There are piano-vocal scores annotated in her own hand as she worked out her roles. And there is a small, intimate artifact: her 1937 school memory book from Public School 189 in Washington Heights, Manhattan - a relic of the New York girl who would become La Divina.

The museum unfolds vertically through the old hotel. On the second floor, four rooms gather the objects, images, and sound of her defining roles - Norma, Tosca, La traviata - and of the master classes she taught at the Juilliard School near the end of her career. The first floor holds written, visual, and audio material on the people and parts that shaped her. The third floor, blessed with a view of the Acropolis, houses a mediatheque and a space for performances and education. And the ground floor does the practical work of any modern museum, serving as shop and café - named, inevitably and perfectly, La Divina.