Rhamnous (Greek: Ῥαμνοῦς), also Ramnous or Rhamnus, was an ancient Greek city in Attica situated on the coast, overlooking the Euboean Strait. Its impressive ruins lie northwest of the modern town of Agia Marina in the municipality of Marathon.
The site was best known in antiquity for its sanctuary of Nemesis] the implacable avenging goddess, her most important in ancient Greece.
Rhamnous is the best-preserved Attic deme site. It was strategically significant on the sea routes and was fortified with an Athenian garrison of ephebes (young men). A fortified acropolis dominates the two small harbours located on either side of it which have silted up extensively since antiquity, and into which grain was imported for Athens during the Peloponnesian War.