Odeon is the name for several ancient Greek and Roman buildings built for music: singing exercises, musical shows, poetry competitions, and the like. The word comes from the Ancient Greek ᾨδεῖον, Ōideion, literally "singing place", or "building for musical competitions"; from the verb ἀείδω, aeidō, "I sing", which is also the root of ᾠδή, ōidē, "ode", and of ἀοιδός, aoidos, "singer".
In a general way the construction of an odeon was similar to that of an ancient Greek theatre, but it was only a quarter of the size and was provided with a roof for acoustic purposes, a characteristic difference. The prototype odeon was the Odeon of Pericles (Odeon of Athens), a mainly wooden building by the southern slope of the Acropolis of Athens. It was described by Plutarch as 'many-seated and many-columned' and may have been square, though excavations have also suggested a different shape, 208 x 62 feet. It was said to be decorated with the masts and spars of ships captured from the Persians. It was rebuilt by king Ariobarzanes I of Cappadocia after destruction by fire in the First Mithridatic War in 87–86 BC.
The oldest known odeon in Greece was the Skias at Sparta, so called from its resemblance to the top of an umbrella, said to have been erected by Theodorus of Samos (600 B.C.); in Athens an odeon near the spring Enneacrunus on the Ilissus was referred to the age of Peisistratus, and appears to have been rebuilt or restored by Lycurgus (c. 330 B.C.). This is probably the building which, according to Aristophanes, was used for judicial purposes, for the distribution of corn, and even for the billeting of soldiers.
The most magnificent odeon was the Odeon of Herodes Atticus on the southwest cliff of the Acropolis at Athens. It was built in about 160 A.D. by the wealthy sophist and rhetorician Herodes Atticus in memory of his wife, and considerable remains of the odeon still exist. It had accommodation for 4500/5500 persons, and the ceiling was constructed of beautifully carved beams of cedar wood, probably with an open space in the centre to admit the light. It was also profusely decorated with pictures and other works of art. Similar buildings also existed in other parts of Greece; at Corinth, also the gift of Herodes Atticus; at Patrae, where there was a famous statue of Apollo; at Smyrna, Tralles, and other towns in Asia Minor. The first odeon in Rome was built by Domitian (Odeon of Domitian), a second by Trajan.