As early as the 12th century, the distinctive character of the city's districts was emerging. The Ile de la Cité, on which the Cathedral of Notre Dame de Paris was built in 1163, was the centre of government and religious life; the Left Bank was the centre of learning, focusing on the various Church-run schools established there; and the Right Bank was the centre of commerce and finance. A league of merchants, the so-called Hanse Parisienne, was established and quickly became a powerful force in the city's affairs.
The area of modern Paris has been inhabited since at least the fourth millennium BC, although little is known about these early inhabitants. The first known permanent settlement on the site was founded about 250 BC by a Celtic tribe called the Parisii, who established a fishing village on the Seine island that was later to become the Ile de la Cité. This was known as Lutetia, a name first recorded by Julius Caesar in his Gallic Wars.
Roman rule in northern Gaul effectively collapsed in the 5th century. In 451 the region was invaded by Attila the Hun, prompting fears that Paris would be attacked. According to legend, the city was saved by the piety of Sainte Geneviève and her followers, whose prayers for relief were answered when Attila's march turned away from Paris to the south. Ste Geneviève remains Paris' patron saint to this day.
Paris is served by two principal airports: Orly Airport, which is south of Paris, and the Charles De Gaulle International Airport in nearby Roissy-en-France. A third and much smaller airport, at the town of Beauvais, 70km (45 miles) to the north of the city, is used by charter and low-cost airlines. Le Bourget airport nowadays only hosts business jets, air trade shows and the aerospace museum.
The city emerged into an energetic but restless interwar period, enlivened by the arrival of glamorous émigrés such as Josephine Baker. It was a troubled political period, however, especially when the Great Depression hit Paris.
The following month, more than 2,000 people were massacred in Paris as revolutionary mobs hunted down and killed anyone seen as an opponent of the new order. The monarchy was formally abolished on 22 September 1792, "Day I of Year I of the French Republic."
Fierce fighting broke out a few days later as government troops retook the city district by district. It only ended on 29 March, by which time an estimated 4,000-5,000 people on both sides had been killed. In the aftermath, another 10,000 Communards were shot, 40,000 were arrested and 5,000 were deported.
The Bois de Boulogne and the Bois de Vincennes were both transformed into large public parks. Although Haussmann was forced to resign in 1869 after financial irregularities, his scheme is largely responsible for the present-day look and layout of Paris.
Matters came to a head on 23 August 1572 with the St Bartholomew's Day Massacre, when Catholic mobs killed an estimated 3,000 Protestants on the instructions of King Charles VIII. His successor, King Henry III, attempted to find a peaceful solution but the city's population turned against him and forced him to flee in May 1588. The following year, he was assassinated by a fanatical Dominican monk, bringing the Valois line to a premature end.
The city's status was reflected in the construction of grandiose new monuments, such as the Arc de Triomphe and the Eglise du Dome in which Napoleon's body was interred. Much of the population, however, lived in appalling conditions in diseased slums; a cholera outbreak in 1831 killed over 19,000 people.
Prior to 1968, département 75 was the Seine département, which contained the city of Paris and its immediate suburbs. The splitting up of the Seine département resulted in the creation of four new départements: Paris proper (75), and three départements (Hauts-de-Seine, Seine-Saint-Denis and Val-de-Marne) forming a ring around Paris, often called la petite couronne (i.e. the "small ring", as opposed to the "large ring" of the more distant suburbs of Paris).
Under de Gaulle's successors, Georges Pompidou and Valéry Giscard d'Estaing, Paris underwent major physical development. The radical Centre Pompidou was built along with the ultra-modern complex at La Villette (originally an abattoir, now a science museum).
In 1870 the Franco-Prussian War ended in a siege of Paris and the Paris Commune, which surrendered in 1871 after a winter of famine and bloodshed. The Eiffel Tower, the best-known landmark in Paris, was built in 1889 in a period of prosperity known as La Belle Époque (The Beautiful period).
Greater Paris metropolitan area, with a total GDP higher than Australia, is the largest financial and business center of continental Europe (on par with London), harboring more than 30% of France's white-collar population, as well as more than 40% of the headquarters of French companies, with the largest business district of Europe (La Défense), and the 2nd largest stock exchange in Europe (Euronext).