Paris is divided into two halves, the left bank, la Rive Gauche, and the right bank, la Rive Droite, by the river Seine. Historically, all government-related buildings have been on the right bank, making it the older and more historic side. Bridges across the river connect the two banks as well as connecting the city to the two natural islands that are found in the middle of the river, Île de la Cité and Île Saint-Louis.
Since the city of Paris is large and has been developed along both sides of the river and on the natural islands, it requires bridges for people to easily travel throughout the different neighborhoods. Parisian streets were planned to accomodate this. WIth 37 bridges that connect the city all throughout, Paris is a unique city. The city of Budapest, in Hungary, is also divided by a river, but Budapest has only eight bridges!
The river, while it may seem to be an obstacle to be crossed, is probably a main reason people gathered in this area and formed the city of Paris. Historically, rivers were important trade routes and water sources, so many cities formed along them.
Today, the river doesn't seem to be an obstacle at all for Parisians.
