Along the right bank of the Seine, the 4th Arrondissement is a lively, multicultural neighborhood that includes the part of Ile de la Cite where the famous Notre Dame can be found. The cathedral dates back to 1163, and featured prominently in Victor Hugo's The Hunchback of Notre-Dame.
The 4th Arrondissement home to the Victor Hugo Museum and the Hotel de Ville (Paris's beautiful city hall) as well. It's known for its nightlife (it's the center of gay nightlife in Paris) as well as shopping. Many top-notch boutiques are open on Sundays (most in other areas aren't) and the Rue des Frances-Bourgeois is lined by upscale shops. For dining, visitors can choose from over 4,000 restaurants. Ile Saint-Louis, however, is the hub of the quaint cafes. But this area is a bit quieter at night; venture off the island once you're ready to party.
Tourists are always bustling through the 4th Arrondissement, making it one of the city's most crowded (and most exspensive) areas -- right up there with the neighboring 1st Arrondissement. But despite the crowds, the 4th Arrondisement is extremely pedestrian-friendly, and it's easy to cover the entire neighborhood on foot (though it involves crossing a couple of bridges).
A central tourist spot in Paris, the 4th Arrondissement is located between the Chatelet and Bastille areas, both of which are major transportation hubs. Though it's an expensive neighborhood, the 4th Arrondissment does have several budget hotels. However, they (and all hotels in the area) book up quickly, so be sure to lock down your acommodations well in advance.