What is the "Second Empire" from No Exit?

Following Napoleon Bonaparte and the temporary return to a monarchy, France established what was called the Second Republic (the First Republic was what resulted from the Revolution in the 1790s). Things changed when Louis Napoleon took power: he named himself Emperor and created the so-called Second Empire, which lasted from 1852 to 1870. Paris owes much of its present form to this epoch. The Opera Garnier, the famous home of Gaston Leroux's Phantom of the Opera, dates back to this period, and was designed by Charles Garnier in a bizarre style that melded French neo-classicism of the Perrault mode with splashes of the Baroque. Baron Haussmann, an Alsatian, began his revamping of Paris in the 1860s, tearing down medieval neighborhoods and cutting across the terrain with great, tree-lined boulevards. The grid formation of Paris's Right Bank and parts of the Left are the creation of Haussmann, and his renovations inspired scores of cities across the world - most famously, New York City.