Most of Barcelona (with the notable exception of the Gothic Quarter and Raval, near the sea) is laid out on a grid. Locals refer to the sea (mar) or mountain (montaña) side of streets to give directions, but for the sake of explanation here, we’ll place the Mediterranean to the south (which it isn’t exactly) and to the north the mountains that you can see from almost anywhere in the city. There are essentially four parts of Barcelona that will interest you most: the Old City of the Romans and the Middle Ages; the 19th-century planned city, called Eixample; the waterfront; and the mountain called Montjüic

In the oldest part of town, les Rambles (pronounced “las ramblas”) is a central north-south artery from Plaça de Catalunya down to the sea. It’s actually a succession of streets, whose names—Rambla de Santa Mònica, Rambla dels Caputxins, Rambla de Sant Josep, Rambla dels Estudis, Rambla de Canaletes—recall the various religious orders that were once located here. To the west of it lies the Raval neighborhood, and to the east, the oldest part of Barcelona: the Barrio Gotico and El Born. The Picasso Museum, the Cathedral, the church of Santa Maria del Mar, and the Palace of Catalan Music are found in the warren of narrow streets holding the Gothic Quarter and the Born neighborhoods. The Raval is home to the Museum of Contemporary Art and the CCCB (Contemporary Center of Catalan Culture), along with lively eateries and shops reflecting the ethnic culture of recent immigrants.

Above the busy hub of Plaça de Catalunya stretches the Eixample, the Catalan word for “expansion,” which is exactly what took place in the second half of the 19th century after Barcelona’s medieval walls were demolished in 1860. Urban planner Ildefons Cerdá freed up the city from the narrow twisting alleys of the Gothic Quarter, shooting his wide thoroughfares and identically spaced blocks of buildings northward, which connected old Barcelona with the village of Gracia; the Rambles were extended beyond Plaça de Catalunya as the Passeig de Gracia (or “the passage to Gracia”), now a chic shopping boulevard.

Beyond Gaudi
If you'd like to explore the city's hidden treasures of Modernisme, those that aren’t open specifically as historic museums, consider putting these beauts on your itinerary: 

Caixa Forum—Near Plaça d’Espanya, this former factory built by the major Modernista architect Puig I Cadalfach re-opened in 2002 as a handsome venue for La Caixa bank’s traveling art exhibitions. If you don’t want to pay for the art shows, you can still roam around the brick pavilions and go up on the undulating rooftop, which you will probably have pretty much to yourself. Av. De Francesc Ferrer i Guárdia, 6-8.

Fundació Mapre—The elegant Casa Garriga Nogués, an extraordinary Modernista mansion by Enric Sagnier in l’Eixample, is now (since 2015) also a space of traveling art exhibitions, which rarely cost more than 3 € to enter. Carrer de Diputació 250. Complete information at www.fundacionmapfre.org/fundacion/en/exhibitions/casa-garriga-nogues. 

Hotel España—This still-operating hotel in Raval was renovated by Doménech I Muntaner in 1903-04 and given another facelift in 2010. Guided tours offered by the hotel (Tues 12:15pm and Fri 4:30pm) highlight Modernista features like the outrageous alabaster fireplace by sculptor Eusebi Arnau, which still dominates one of the dining rooms. Carrer de Sant Pau 9-11, www.hotelespanya.com.

Palau Baró de Quadras—Open by appointment only, the former residence at Av. Diagonal 373 has been chopped up over the years, but many stunning original elements are still intact. To make an appointment, contact Cases Singulars at www.casessingulars.com. 

Want to see more in the company of a local expert? Try the architectural tours at Insight Barcelona (www.insight-barcelona.com); their tours access a number of sites that aren’t usually open to the public.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.