ARCADE, in Architecture, is used to denote any opening formed by an arch in the wall of a building. ARCADIA, a very mountainous country in the centre of Peloponnesus, bounded on the north by Achaia, east by Argolis, west by Elis, and south by Messenia and Laconia. Its greatest length was about 50 miles, and its breadth from 35 to 41 miles. The Alpheus and its tributaries were its principal rivers. The Arcadians derived their origin from the eponymous hero Arcas; and they are called by the Greek writers autochthones, or aborigines. Their great tutelary deity was Pan, who presided over rural affairs. The Arcadians were a simple and frugal people, and especially fond of music, which they cultivated with great success. When the rest of Peloponnesus was conquered by the Dorians, they maintained their independence. They were originally governed by kings; but about the year 670 B.C. they abolished monarchy, and their several cities—the most important of which were Mantinea, Orchomenus, Tegea, Pheneos, and Psophis—became independent republics. The Arcadians joined the Achaean League, and finally submitted to the Romans.