Barcelona is made up of three main zones. The old city (Ciutat Vella) lies between Plaça de Catalunya and the port and breaks down into the Rambla; the Barri Gotic (Gothic Quarter); the Barri de la Ribera (Waterfront Quarter); the Raval, or medieval "outskirts" west of the Rambla; and Barceloneta, the old fishing quarter.

Above the old city is the grid-patterned expansion built after the city's third set of walls was torn down in 1860. Known as the Eixample ("Widening"), this area contains most of Barcelona's Moderniste architecture. Farther out are the former outlying towns of Gràcia, Sarrià, and Pedralbes, and looming up behind are Tibidabo and the Collserola hills. South of Barcelona proper lies the hill of Montjuïc, on which are several of the sights most worth seeing.

Barcelona's main cross-town traffic arteries are the Diagonal (so called because it runs diagonal to the longitudinal line through the city) and the midtown speedways Carrer d'Aragó and Gran Via de les Corts Catalanes, both cutting northeast-southwest through the heart of the city.

Passeig de Gràcia, which becomes Gran de Gràcia above the Diagonal, runs all the way from Plaça de Catalunya to Plaça de Lesseps, but the main up and down streets, for motorists, are Balmes, Muntaner, Aribau, and Comtes d'Urgell. Because of general noise and air pollution, you should avoid walking these streets (with the possible exception of Passeig de Gràcia, which is unavoidable because of its dense endowment of Moderniste architecture) and instead take the charming and leafy Rambla de Catalunya, which is the upper extension of the Rambla between Plaça de Catalunya and the Diagonal.