Admission to archaeological sites, historical sites, monuments and museums owned by the State and managed by the Hellenic Ministry of Culture and Sports is free of charge for all visitors, on the following dates:

• 6 March  (in memory of Melina Mercouri)
• 18 April  (International Monuments Day)
• 18 May  (International Museums Day)
• The last weekend of September annually (European Heritage Days)
• 28th October  (National Holiday), and
• every first Sunday of each month from November 1^st until March 31^st

All the caterogies of visitors entitled to free entrance in any day are here https://www.culture.gov.gr/en/service/SitePages/view.aspx?iID=2695