History of Paris
Paris began as the Celto-Roman settlement of Lutetia on the Île de la Cité. It takes its present name from the name of the dominant Gallo-Celtic tribe in the region, the Parisii. At least that's what the Romans called them, when the showed up in 52 BCE and established their city Lutetia on the left bank of the Seine, in what is now called the "Latin Quarter" in the 5th arrondissement.
The Romans held out here for as long as anywhere else in the Western Empire, but by 508 they were gone, replaced Clovis of the Franks, who is considered by the French to be their first king.
Clovis' decendants, a.k.a. the Carolingians, held on for nearly 500 years though Viking raids and other calamities forced a move by most of the population back to the islands which had been the center of the celtic village. The Capetian duke of Paris was voted to succeed the last of the Carolingians as king of France, ensuring the city of its premier position in the medieval world.
Over the next several centuries Paris expanded onto the right bank into what was called "the Marais." Quite a few buildings from this time can be seen in the 4th arrondissement.
The medieval period also witnessed the founding of the Sorbonne which as "the University of Paris" became one of if not the most important center for learning in Europe if not the whole world for several hundred years. Most of the institutions which are a part of the University are found in the 5th, and 13th arrondissements.
The Capetian and later the Bourbon kings of France made their mark on Paris with such buildings as the Louvre and the Palais Royal, both in the 1st, but the Paris which most visitors know and love was built long after they were gone in the 19th century when Baron von Hausmann reconstructed adding the long straight avenues, and demolishing many of the medieval houses which had been left until that time.
New wonders arrived during la Belle Époque, as the Parisien golden age of the late 19th century is known. Gustave Eiffel's famouse tower, the first metro lines, most of the parks, and the streetlights which gave the city its epethet "the city of light" all come from this period.
The 20th century was hard on Paris, but thankfully not as hard as it could have been. Hitler's order to burn the city was thankfully ignored by the german General von Choltitz who was quite possibly convinced by a swedish diplomat that it would be better to surrender and be remembered as the savior of Paris, then to be remembered as its destroyer.
Following the war the city recovered slowly at first, and then more quickly in the 1970s and 1980s when Paris began to experience some of the problems faced by big cities everywhere: pollution, housing shortages, and occasionally failed experiments in urban renewal. During this time however Paris enjoyed considerable growth as a multi-cultural city, with new immagrants from all corners of the world, especially francophonie, including most of northern and western Africa as well as Vietnam and Laos. These immigrants brought their foods and music both of which are of prime interest for many travellers.
Immigration and multi-culturalism continues in Paris today. The 21st century has seen a marked increase in the arrival of people from latin america, especially Mexico, Columbia, and Brazil. In the late 1990's it was hard to find good Mexican food in Paris, for instance, today there are dozens of possibilities from lowly taquerias in the outer arrondissements to nice sit-down restaurants on the boulevards. The chili pepper has arrived. Meanwhile Latin music from Salsa to Samba is all the rage (well, alongside Paris lounge electronica).
The 21st century has also seen vast improvements in the general livibility of Paris, with the Mayor's office concentrating on reducing pollution and improving facilities for soft forms of transportation including a huge network of cycle paths, larger pedestrian districts and newer faster metro lines. Visitors who normally arrive car-less are the benificiaries of these policies as much as the Parisiens themselves are.
Source: Wikipedia under GFDL.