The Teatro alla Scala (or La Scala, as it is known), in Milan, Italy, is one of the world's most famous opera houses. The theatre was inaugurated on 3 August 1778, under the name Nuovo Regio Ducal Teatro alla Scala with Salieri's Europa riconosciuta.

A fire destroyed the previous theatre, the ancient Teatro Ducale, on 25 February 1776, after a carnival gala. A group of ninety wealthy Milanese, who owned palchi (private boxes) in the theatre, wrote to Archduke Ferdinand I of Austria asking for a new theatre and a provisional one to be used while completing the new one. The neoclassical architect Giuseppe Piermarini produced an initial design but it was rejected by Count Firmian (an Austrian governor).

A second plan was accepted in 1776 by Empress Maria Theresa. The new theatre was built on the former location of the church of Santa Maria della Scala, from which the theatre gets its name. The church was deconsecrated and demolished, and over a period of two years the theater was completed by Pietro Marliani, Pietro Nosetti and Antonio and Giuseppe Fe. This theatre had a total over 3,000 seats organized into 678 pit-stalls, arranged in six tiers of boxes above which is the 'loggione' or two galleries. Now the stage is one of the largest in Italy (16.15m d x 20.4m w x 26m h).

Building expenses were covered by the sale of palchi, which were lavishly decorated by their owners, impressing observers such as Stendhal. La Scala (as it soon became to be known) soon became the preeminent meeting place for noble and wealthy Milanese people. In the tradition of the times, the platea (the main floor) had no chairs and spectators watched the shows standing up. The orchestra was in full sight, as the golfo mistico (orchestra pit) had not yet been built.

Above the boxes, La Scala has always had a gallery where the less wealthy can watch the performances. It is called the loggione. The loggione is typically crowded with the most critical opera aficionados, who can be ecstatic or merciless towards singers' perceived successes or failures. La Scala's loggione is considered a baptism of fire in the opera world, and fiascos are long remembered. One recent incident occurred in 2006 when tenor Roberto Alagna was booed off-stage during his performance, forcing a non-wardrobed understudy to replace him mid-concert. As with most of the theaters at that time, La Scala was also a casino, with gamblers sitting in the foyer.

La Scala was originally illuminated with eighty-four oil lamps mounted on the palcoscenico and another thousand in the rest of theater. To prevent the risks of fire, several rooms were filled with hundreds of water buckets. In time, oil lamps were replaced by gas lamps, these in turn were replaced by electric lights in 1883.

The original structure was renovated in 1907, when it was given its current layout with 2,800 seats. In 1943, during WWII, La Scala was severely damaged by bombing. It was rebuilt and reopened on May 11 1946, with a memorable concert conducted by Arturo Toscanini, with a soprano solo by Renata Tebaldi, which created a sensation.

La Scala hosted the prima (first production) of many famous operas, and had a special relationship with Giuseppe Verdi. For several years, however, Verdi did not allow his work to be played here, as some of his music had been modified (he said "corrupted") by the orchestra. This dispute originated in a disagreement over the production of his Giovanna d'Arco in 1845; however the composer later conducted his Requiem there on May 25 1874, and in 1886 announced that La Scala would host the premiere of his opera Otello. The premiere of his last opera, Falstaff was also given in the theatre.

La Scala's season traditionally opens on 7 December, Saint Ambrose's Day, Milan's patron saint. All performances must end before midnight; long operas start earlier in the evening if need be. Ticketholders are not allowed to enter after the performance has begun. No exceptions are made, as Richard Burton once discovered.

The La Scala Museum (Museo Teatrale alla Scala), accessible from the theatre's foyer and a part of the house, contains an extraordinary collection of paintings, drafts, statues, costumes, and other documents regarding opera and La Scala's history.

La Scala also hosts the Accademia d’Arti e Mestieri dello Spettacolo (Academy for the Performing Arts). Its goal is to train a new generation of young musicians, technical staff, and dancers (at the Scuola di Ballo del Teatro alla Scala, one of the Academy's divisions).