The Pelasgic wall or Pelasgian fortress or Enneapylon (nine-gated) was a monument supposed to have been built by the Pelasgians

Pelasgians

The name Pelasgians was used by some ancient Greek writers to refer to populations that were either the ancestors of the Greeks or who preceded the Greeks in Greece, "a hold-all term for any ancient, primitive and presumably indigenous people in the Greek world." In general, "Pelasgian" has come...

, after levelling the summit of the rock on the Acropolis of Athens

Acropolis of Athens

The Acropolis of Athens or Citadel of Athens is the best known acropolis in the world. Although there are many other acropoleis in Greece, the significance of the Acropolis of Athens is such that it is commonly known as The Acropolis without qualification...

. Thucydides

Thucydides

Thucydides was a Greek historian and author from Alimos. His History of the Peloponnesian War recounts the 5th century BC war between Sparta and Athens to the year 411 BC...

 and Aristophanes

Aristophanes

Aristophanes , son of Philippus, of the deme Cydathenaus, was a comic playwright of ancient Athens. Eleven of his forty plays survive virtually complete...

 call it "Pelargikon", "Stork wall or place". The Parian Chronicle

Parian Chronicle

The Parian Marble or Parian Chronicle is a Greek chronological table, covering the years from 1581 BC to 264 BC, inscribed on a stele...

 mentions that the Athenians expelled the Peisistratids from the "Pelasgikon teichos". Herodotus

Herodotus

Herodotus was an ancient Greek historian who was born in Halicarnassus, Caria and lived in the 5th century BC . He has been called the "Father of History", and was the first historian known to collect his materials systematically, test their accuracy to a certain extent and arrange them in a...

 relates that before the expulsion of the Pelasgians from Attica, the land under Hymettus

Hymettus

Hymettus, also Hymettos is a mountain range in the Athens area, East Central Greece. It is also colloquially known as Trellos or Trellovouno , a name of uncertain origin...

had been given to the them as a dwelling-place in reward for the wall that had once been built around the Acropolis.