The Palais Garnier has been called "probably the most famous opera house in the world, a symbol of Paris like Notre Dame Cathedral, the Louvre, or the Sacré Coeur Basilica".

The façade of the Opera used seventeen different kinds of material, arranged in very elaborate multicolored marble friezes, columns, and lavish statuary, many of which portray deities of Greek mythology.

[21] The two gilded figural groups, Charles Gumery's L'Harmonie (Harmony) and La Poésie (Poetry), crown the apexes of the principal façade's left and right avant-corps.

The woman representing industry holds a lead pig and a hammer, while a winged genius stands at her feet, carrying a cup full of jewels.

[23] Gilded galvanoplastic bronze busts of many of the great composers are located between the columns of the theatre's front façade and depict, from left to right, Rossini, Auber, Beethoven, Mozart, Spontini, Meyerbeer, and Halévy.

On either side of the stage gable wall are two identical bronze sculptures by Eugène-Louis Lequesne representing Fame holding back Pegasus.

The interior consists of interweaving corridors, stairwells, alcoves and landings, allowing the movement of large numbers of people and space for socialising during intermission.

The ceiling above the staircase was painted by Isidore Pils to depict The Triumph of Apollo, The Enchantment of Music Deploying its Charms, Minerva Fighting Brutality Watched by the Gods of Olympus, and The City of Paris Receiving the Plan of the New Opéra.

Then there were talks about moving the La Danse (Carpeaux) from the main façade, but instead Garnier chose the Pythia by Adèle d'Affry (the artist also known by the pseudonym Marcello).

In two of the panels the scenes are more erotic (Artemis - Endymion, Eos - Cephalus), while the other two depict the couples leaving the underworld and are more about death than love (Hermes - Psyche, Orpheus - Eurydice).

[32] The decoration framing the mosaic panels with the mythological couples include theatre masks, musical instruments, birds, all surrounded by flowers, fruits and gold.

It depicts scenes from operas by 14 composers – Mussorgsky, Mozart, Wagner, Berlioz, Rameau, Debussy, Ravel, Stravinsky, Tchaikovsky, Adam, Bizet, Verdi, Beethoven, and Gluck.

What else could offer the variety of forms that we have in the pattern of the flames, in these groups and tiers of points of light, these wild hues of gold flecked with bright spots, and these crystalline highlights?

[46] On 29 September 1860 an Imperial Decree officially designated the site for the new Opéra,[47] which would eventually occupy 12,000 square metres (1.2 ha; 130,000 sq ft).

The new submissions were sent to the jury in the middle of May, and on 29 May 1861 Garnier's project was selected for its "rare and superior qualities in the beautiful distribution of the plans, the monumental and characteristic aspect of the façades and sections".

[53] Garnier's wife Louise later wrote that the French architect Alphonse de Gisors, who was on the jury, had commented to them that Garnier's project was "remarkable in its simplicity, clarity, logic, grandeur, and because of the exterior dispositions which distinguish the plan in three distinct parts—the public spaces, auditorium, and stage ... 'you have greatly improved your project since the first competition; whereas Ginain [the first-place winner in the first phase] has ruined his.

A giddy mixture of up-to-the-minute technology, rather prescriptive rationalism, exuberant eclecticism and astonishing opulence, Garnier's opera encapsulated the divergent tendencies and political and social ambitions of its era.

It incorporated a water course and an enormous concrete cistern (cuve) which would both relieve the pressure of the external groundwater on the basement walls and serve as a reservoir in case of fire.

After previewing it, the emperor requested several changes to the design of the building, the most important of which was the suppression of a balustraded terrace with corner groups at the top of the façade and its replacement with a massive attic story fronted by a continuous frieze surmounted by imperial quadrigae over the end bays.

The linear frieze seen in the model was also redesigned with alternating low- and high-relief decorative medallions bearing the gilded letters from the imperial monogram ("N" for Napoléon, "E" for Empereur).

The official title of the Paris Opera was prominently displayed on the entablature of the giant Corinthian order of coupled columns fronting the main-floor loggia: "ACADEMIE IMPERIALE DE MUSIQUE".

[64] In spite of this, when it came time to change the name on the new opera house, only the first six letters of the word IMPERIALE were replaced, giving the now famous "ACADEMIE NATIONALE DE MUSIQUE", an official title which had actually only been used during the approximately two-year period of the Second Republic which had preceded the Second Empire.

Because of the theatre's proximity to the fighting at the Place Vendôme, troops of the National Guard bivouacked there and were in charge of its defence and distributing food to soldiers and civilians.

The Commune authorities planned to replace Garnier with another architect, but this unnamed man had not yet appeared when Republican troops ousted the National Guard and gained control over the building on 23 May.

Economies were demanded, and Garnier was forced to suppress the completion of sections of the building, in particular the Pavillon de l'Empereur (which later became the home of the Opera Library Museum).

The cash-strapped government of the Third Republic resorted to borrowing 4.9 million gold francs at an interest rate of six percent from François Blanc, the wealthy financier who managed the Monte Carlo Casino.

[67] During 1874 Garnier and his construction team worked feverishly to complete the new Paris opera house, and by 17 October the orchestra was able to conduct an acoustical test of the new auditorium, followed by another on 2 December which was attended by officials, guests, and members of the press.

[68] The theatre was formally inaugurated on 5 January 1875 with a lavish gala performance attended by Marshal MacMahon, the Lord Mayor of London and King Alfonso XII of Spain.

In 1969, the theatre was given new electrical facilities and, during 1978, part of the original Foyer de la Danse was converted into new rehearsal space for the Ballet company by the architect Jean-Loup Roubert.

This consisted of modernizing the stage machinery and electrical facilities, while restoring and preserving the opulent décor, as well as strengthening the structure and foundation of the building.