The Place du Châtelet (French pronunciation: [plas dy ʃɑtlɛ]) is a public square in Paris, on the right bank of the river Seine, on the borderline between the 1st and 4th arrondissements. It lies at the north end of the Pont au Change, a bridge that connects the Île de la Cité, near the Palais de Justice and the Conciergerie, to the right bank. The closest métro station is Châtelet 
Châtelet–Les Halles station (French: [ʃɑtlɛ le al]) is a major train hub in Paris and the largest underground station in the world. Opened in 1977, it is the central transit hub for the Paris metropolitan area, connecting three of five RER commuter-rail lines and five of sixteen Métro lines. The hub hosts 750,000 travellers per weekday (493,000 for the RER alone) and platforms separated by up to 800 metres (0.5 mi). It is named after the nearby Place du Châtelet public square and Les Halles, the former wholesale food market of Paris, now a shopping mall.
Châtelet station (French pronunciation: [ʃɑtlɛ]) is a station of the Paris Métro and Île-de-France's RER commuter rail service, located in the centre of medieval Paris, on the border between the 1st and 4th arrondissements. It serves RER A, B and D, as well as lines 1, 4, 7, 11, and 14 of the Paris Métro; it is the southern terminus of Line 11. The station is made up of two parts connected by a long corridor: lines 7 and 11 under the Place du Châtelet and the Quai de Gesvre (site of the original medieval river port of Paris), next to the Seine; lines 1, 4 and 14 towards Rue Saint-Denis and the Rue de Rivoli.
Châtelet is connected by another long underground corridor to the southern end of the RER platforms at Châtelet–Les Halles, the northern end of which is again connected to the métro station Les Halles. The distance from Line 7 at Châtelet to the RER lines at Châtelet–Les Halles is approximately 750 metres (2,460 ft). It is the ninth-busiest station on the métro system.
Gabriel Jean Antoine Davioud (French: [ʒɑ̃ ɑ̃twan ɡabʁijɛl davju]; 30 October 1824 – 6 April 1881) was a French architect, a representative of eclecticism in architecture. He worked closely with Baron Haussmann on the transformation of Paris under Napoleon III during the Second Empire. Davioud is remembered for his numerous contributions to Parisian architecture, notably the now-former Trocadéro Palace, which he co-designed with Jules Bourdais, the two theatres on the Place du Châtelet (Théâtre du Châtelet and Théâtre de la Ville), the Fontaine Saint-Michel, as well as urban amenities such as pavilions, benches and kiosks. These contributions now form an integral part of the style of Haussmann's Paris.
The Tribunal de commerce de Paris ("Paris commercial court[house]"), until 1968 Tribunal de commerce de la Seine, refers both to the tribunal de commerce of Paris, a commercial court, and to the building that hosts it on the Île de la Cité in Paris. Because that building's main entrance is on the quai de la Corse, the phrase Quai de la Corse is used as a nickname for the court, not least with reference to its role in corporate insolvencies.
Les Troyens (pronounced [le tʁwajɛ̃]; in English: The Trojans) is a French grand opera in five acts, running for about five hours, by Hector Berlioz. The libretto was written by Berlioz himself from Virgil's epic poem the Aeneid; the score was composed between 1856 and 1858. Les Troyens is Berlioz's most ambitious work, the summation of his entire artistic career, but he did not live to see it performed in its entirety. Under the title Les Troyens à Carthage, the last three acts were premièred with many cuts by Léon Carvalho's company, the Théâtre Lyrique, at their theatre (now the Théâtre de la Ville) on the Place du Châtelet in Paris on 4 November 1863, with 21 repeat performances. The reduced versions run for about three hours. After decades of neglect, today the opera is considered by some music critics as one of the finest ever written.