The Archaeological Museum, which was founded between 1834-35, is housed under the sumptuous Town Hall of Ermoupoli. Through the ages, the museum has been hosted in many different places: in the city's High School, then (in 1888) in a municipal building near the Nisaki neighbourhood and in the Municipality between 1899-1901.
Exhibits of the hellinistic and roman period are displayed here: sculptures, funerary steles and inscriptions found in Ermoupoli. Some archaeological findings of other parts of Greece are kept here: reliefs from Amorgos and Kythnos Islands and other items found in Aegina island, Beotia and elsewhere. However, the largest and most representative exhibits of the museum come from the excavations in Chalandriani. Large parts of an ancient fortification (in the location of Kastri), ruins of houses, metal workshops and potteries were revealed in this important early Cycladic settlement, dating to the second half of the 3rd millenium BC, between 2400/2300-2100 BC. Most of the archaeological items are votive offerings (marble, clay or metal objects) found in the 600 tombs of this site.