Athens is the largest municipality in Greece by population.
The Municipality of Athens had 643,452 residents in the 2021 census, placing it ahead of the Municipality of Thessaloniki. It occupies only the historic capital’s central administrative area, rather than the whole continuously built-up Athens urban area or the broader metropolitan region.
Athens has been a major settlement for more than 3,400 years and became the capital of modern Greece in 1834. Its municipality is divided into seven municipal communities and forms the historic and administrative core of a much larger urban region in Attica.
A frequent mix-up is treating “Athens” as the entire metropolitan area. Greater Athens contains many separate municipalities, including Piraeus, Peristeri and Kallithea. The question specifically asks for the largest municipality, where Athens remains first; Thessaloniki is second at the municipality level.