First Opera House in Italy: Teatro Olimpico (1580–1585), Not a True Opera House

There is no record of a purpose-built "opera house" in Italy in a single year—because opera as a genre emerged gradually. However, the Teatro Olimpico in Vicenza is the oldest surviving intact theatre in the world.

• Built: 1580–1585
• Architect: Andrea Palladio (completed by Vincenzo Scamozzi)
• Style: Renaissance masterpiece; indoor Roman-style theatre with forced-perspective stage set.
• First performance: Oedipus Rex (Sophocles), 1585.

True opera houses came later:

• Teatro San Cassiano, Venice (1637) — first public opera house (ticketed).
• La Scala, Milan (1778) — most famous.
• Teatro alla Scala, Teatro La Fenice, Teatro San Carlo — 18th-century icons.

Teatro Olimpico is a theatre, not an opera house—but it's the oldest surviving venue where opera could be (and later was) performed.