MEGALOPOLIS, an ancient city of Arcadia, Greece, in a plain about 20 m. S.W. of Tegea, on both banks of the Helisson, about 21 m. above its junction with the Alpheus. It was founded by the Theban general Epaminondas in 370 B.C., as a bulwark for the southern Arcadians against Sparta, and as the seat of the Arcadian Federal Diet. The builders were protected by a Theban force, and directed by ten native oecists (official "founders"), who drew inhabitants from all parts of Arcadia, but especially from Maenalia and Parrhasia. Forty townships are mentioned by Pausanias (viii. as having been incorporated in it. It was 5o stadia in circumference, and was surrounded with strong walls. Its territory was the largest in Arcadia, extending northward 24 m. The city was adorned with many handsome buildings. Its temples contained ancient statues brought from the incor porated towns. After the departure of Epaminondas, Lycomedes of Mantineia succeeded in drawing the Arcadian federation away from its alliance with Thebes, and it was consequently obliged to make common cause with Athens. Its attempt to use the treasures of Olympia led to dissensions, and in the battle of Mantineia (362) one-half of the Arcadians fought on the side of the Spar tans, the other on that of the Thebans. After this battle many inhabitants of Megalopolis sought to return to their former homes, and it was only by the assistance of three thousand Thebans under Pammenes that they were prevented. In 353, when Thebes was preoccupied with the Sacred War, the Spartans attacked Mega lopolis; but with Theban help the city was rescued. It was at this crisis that a Megalopolitan appeal to Athens, occasioned the oration of Demosthenes, On the people of Megalopolis. The Spartans now concluded peace with Megalopolis and acknowl edged its autonomy. But their hostility did not cease, and Mega lopolis entered into friendly relations with Philip of Macedon. Twenty years later, when the Spartans and their allies rebelled against Macedon, Megalopolis, loyal to its allegiance, stood a long siege. After the death of Alexander, it was governed by native tyrants. In the war between Cassander and Polyperchon it supplied 15,00o men to the former and was besieged by the latter. In 234 B.c. Lydiades, the last tyrant of Megalopolis, re signed, and the city joined the Achaean League, earning again the hatred of Sparta. In 222 Cleomenes plundered it, but in the next year its inhabitants were reinstated by Philopoemen, a native of the city. After. this, it sank into insignificance and in the time of Pausanias it was in ruins. Its only great men were Philopoemen
and Polybius the historian. Lycartas, the father of the latter, may be accounted a third. In the time of Pausanias, the city was mostly in ruins.
The site was excavated by the British School at Athens in 189o–I892. The description of Pausanias tallies closely with the reality. The town was divided into two approximately equal parts by the river Helisson, which flows through it from east to west. The line of the walls may be traced, partly by remains, partly by the contours it must have followed, and confirms the estimate of Polybius that they had a circuit of 5o stades, or about 51 miles. The foundations, formerly supposed to belong to a bridge, are substructures of the precinct of Zeus Soter. The buildings north of the river were municipal, grouped round the square agora. The portico of Philip, on the N., was 30o ft. long, with three rows of columns running its whole length, and a projecting wing at either end. East of it stood the municipal offices (Archeia). At the south-west is the precinct of Zeus Soter, surrounded by a double colonnade, with a small temple on the west and an en trance on the east. In the midst was a substructure either for an altar or for the great group of Zeus and Megalopolis. North of this the Stoa Myropolis formed the E. boundary. These build ings were of various dates, but harmonious plan. On the S. bank of the river were the chief federal buildings, the theatre (noted by Pausanias as the largest in Greece), and the Thersilion or parliament hall ; the great portico of the Thersilion facing the orchestra of the theatre. In consequence, the plan of the theatre is abnormal, for the portico, which has its base about 4 ft. 6 in. above the level of the orchestra, was too lofty for a proscenium; yet, a proscenium of the ordinary type would hide the lower part of the columns. Such a proscenium was actually erected later; but beneath it were foundations for a wooden proscenium, probably erected only when required. Later, steps were added, from the portico to the orchestra. The theatre was probably used, as at Athens, for political assemblies; but the adjoining Thersilion provided cover for the "ten thousand" in wet weather. It is unique in plan, its floor sloping up towards all sides like a theatre, with roof-columns set radially so as to obscure as little as possible the view from the centre.
See Society for the Promotion of Hellenic Studies, Excavations at Megalopolis (1892) ; W. Dorpfeld, Das griechische Theater; 0. Puch stein, Griechische Biihne; s.v.