The Roman theater of Orange was built in ancient Arausio, a colony established for veterans of Rome's Second Legion in the late first century BCE. The town stood beside important routes through the Rhône Valley, where settlement, farming, and imperial administration supported rapid development. During the early Empire, builders placed a theater against the hill now called Saint-Eutrope. Its position used the slope to support the auditorium while a monumental stage building proclaimed the colony's place within the political and cultural order of Roman Gaul.

The surviving stage wall rises to an exceptional height and preserves the architectural enclosure that most ancient theaters have lost. Behind the performance platform, doors, niches, columns, and sculpture once created a richly ornamented façade. A statue of an emperor traditionally identified as Augustus remains a focal point, though restoration has shaped its presentation. Thousands of spectators occupied the semicircular seating according to rank. Drama, music, pantomime, and civic ceremony made the theater an instrument of entertainment, public assembly, and the display of imperial authority.

The complex included neighboring religious and public spaces, tying performance to the broader civic landscape. Its sophisticated acoustics depended on the relationship among seating, stage, wall, and roof rather than on a single architectural trick. As Christianity spread and imperial institutions changed, the theater ceased to function in its original way. The great wall survived because later communities found practical uses for the enclosure. Military, residential, and storage functions gradually replaced performance, while stone and decorative elements were removed or reused elsewhere in the town.

During the Middle Ages and early modern period, houses crowded into the ancient structure, and episodes of conflict gave it defensive and refuge roles. Nineteenth-century preservation campaigns cleared later occupation and began restoring the auditorium. Performances returned in the later nineteenth century, eventually developing into the celebrated Chorégies d'Orange. Restoration recovered a powerful sense of the Roman building but necessarily changed its accumulated urban fabric. Modern roofing and technical installations have also been introduced to protect the stage area and support continued use.

UNESCO inscribed the theater, its surroundings, and Orange's triumphal arch in 1981. Conservation balances fragile stone, sculpture, weather exposure, vibration, and the equipment required by large performances. Archaeological study continues to distinguish original construction from later repair and reconstruction. Orange is significant for preserving the enclosing architecture of a Roman theater on a remarkable scale. Its continuing performance history also shows how a monument can regain an ancient function after centuries of radically different use, while remaining a product of both Roman engineering and modern conservation choices.