The underground labyrinth built by Haussmann also provided gas for heat and for lights to illuminate Paris. At the beginning of the Second Empire, gas was provided by six different private companies. Haussmann forced them to consolidate into a single company, the "Compagnie parisienne d'éclairage et de chauffage par le gaz", with rights to provide gas to Parisians for fifty years. Consumption of gas tripled between 1855 and 1859. In 1850 there were only 9000 gaslights in Paris; by 1867, the Paris Opera and four other major theaters alone had fifteen thousand gas lights. Almost all the new residential buildings of Paris had gaslights in the courtyards and stairways; the monuments and public buildings of Paris, the arcades of the Rue de Rivoli, and the squares, boulevards and streets were illuminated at night by gaslights. For the first time, Paris was the City of Light.