Arrondissement - Paris is divided up into twenty arrondissements or districts. The "First" is in the center of the city, and the others are laid out in a clockwise manner about this. As these are such a basic unit to the city, they are constantly referred to in guides and literature; almost always using simply their associated number (1er, or 2ème etc). The Louvre is in the First, the Arc de Triomphe is in the Eighth. NB: You can determine the arrondissement of an address from its postal code. The last two digits of a Paris address give the arrondissement; 75018 is the eighteenth for example. The exception to this rule are addresses with the word " CEDEX " appearing in them.