Paris By Arrondissement
Paris is divided into 20 districts, called "Arrondissements". These are numbered 1 to 20, starting fron the center of the city (known as "the 1st") and spiral out in sequence to the 20th, which is at the east edge of Paris.
Below are links to pages about each arrondissement:
1st Arr.: The Palais Royal, Les Halles & The Beaubourg
4th Arr.: The Marias
18th Arr.: Montmartre