Geography and history have combined to give Paris a remarkably coherent and intelligible structure. The city lies in a basin surrounded by hills. It is very nearly circular, confined within the limits of the the ring road, the boulevard périphérique, which follows the line of the city's nineteenth-century fortifications. The capital's raison d'être and its lifeline, the River Seine , flows east to west, carving the city in two. Anchored at the hub of the circle, in the middle of the river, is the island from which the rest of Paris grew: the Île de la Cité , home of the capital's oldest religious and secular institutions - Notre Dame cathedral and the Palais de Justice. 

The north or Right Bank ( rive droite ) of the Seine is characterized by imposing government buildings, sweeping vistas and elegant boulevards. The longest and grandest thoroughfare is the so-called Voie Triomphale , which runs from the Louvre to the Grande Arche de la Défense in the northwest, taking in the Tuileries gardens, Champs-Élysées and Arc de Triomphe, each monument an expression of royal or state power across the centuries. To the immediate north and east of the Voie Triomphale spread the commercial and financial quarters, site of the stock exchange, the refurbished nineteenth-century passages and Les Halles shopping centre. Just to the east of Les Halles lie the Marais and Bastille quartiers, two of the city's liveliest and most happening areas. 

The south bank of the river, or Left Bank ( rive gauche ), owes its existence to the cathedral school of Notre-Dame, which spilled over from the Île de la Cité and became the university of the Sorbonne, attracting scholars and students from all over the medieval world. Ever since, it has been the traditional domain of academics, writers and artists. 

The city is divided into twenty arrondissements , whose spiral arrangement provides a fairly accurate guide to its historical growth . Centred on the Louvre, they wind outwards in a clockwise direction. The inner hub of the city comprises arrondissements 1er to 6e, and it's here that most of the major sights and museums are to be found. The outer or higher-number arrondissements were mostly incorpor ated into the city in the nineteenth century - some, such as Montmartre, Belleville and Passy , have succeeded in retaining something of their separate village identity. Historically, the districts to the west attracted the aristo cracy and the newly rich, while those to the east accommodated mainly the poor and the working class, distinctions which largely hold true to this day, though much of the east is gradually being gentrified. 

Paris is not particularly well endowed with parks. The largest, the Bois de Boulogne and the Bois de Vincennes , at the western and eastern limits of the city respectively, do possess small pockets of interest, but are largely anonymous sprawls. For a break from the bustle of the city, it is best to try an out-of-town excursion, to the gardens of Giverny , for example, or the forest of Fontainebleau .