Easton's Bible Dictionary (1897)
” But it denotes also the council or court of justice which met in the open air on the hill. It was a rocky height to the west of the Acropolis at Athens, on the south-east summit of which the council was held which was constituted by Solon, and consisted of nine archons or chief magistrates who were then in office, and the ex-archons of blameless life. On this hill of Mars (Gr. Ares) Paul delivered his memorable address to the “men of Athens” (Acts 17:22-31).
Smith's Bible Dictionary (1863)
[Mars Hill’ HILL]
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
AREOP'AGUS (hill of Mars), a rocky hill near the centre of the ancient city of Athens, and west of the Acropolis, from which it is divided by a valley. It had its name from the tradition that Mars (Ares), the god of war, was tried here by the other gods on the charge of murder. It was celebrated as the place where the great court of justice, the most ancient and venerable of the Athenian courts, was held, and where Paul made his address to the Athenians. Acts 17:19-34.
Near by were the temple of Mars, the Parthenon, the colossal statue of Minerva, and beneath the hill were the caves of the Furies. There are 16 stone steps now to be seen, cut into the rock and leading to its summit, and above the steps there is a bench of stones excavated in the rock, forming three sides of a quadrangle and facing the south.
Here the Areopagites sat as judges, in the open air, and from here Paul made known to the Athenians the "unknown God" and converted one of the judges, Dionysius, who is said to have been the first bishop of Athens and the writer of books on mystical Platonic theology and philosophy.
Hitchcock's Bible Names (1869)
the hill of Mars