Ajuntament de Barcelona

The plain of Barcelona

Miramar Garden and Camí dels Cims

    Barcelona sits on a plain, know as plain of Barcelona, that is delimited by the sea, on the East side, by Collserola mountain range, on the West side, and by the rivers Besòs, on the North side, and Llobregat, on the South side. 

    The rivers Llobregat and Besòs have acted as natural paths to pass the Litoral mountain range and mark old routes to Occitan lands and to supply the town. The plain is established over a support made of rocks from different geological stages. At Collserola mountain range and the hills of Carmel, La Rovira, La Peira and El Putxet, which emerge at different places of the town, it can be observed the oldest materials, made basically by Palaeozoic metamorphic rocks. On the Cenozoic era, Montjuïc emerged. And from the Quaternary period, the plain of Barcelona has been formed by the accumulation of sediments that are swept out by the many torrents and arroyos on Collserola and by the rivers, which are then deposited on the coast by the ocean currents.


    The geological structure over which Barcelona sits is relatively complex, because it is made of several minor tectonic units that are affected by faults: Tibidabo fault, Turons fault, Barcelona fault and El Morrot fault.

    The subsoil of the plain of Barcelona is made of layers of geologically very different materials. The deepest layers are mainly slates with some granitic formations, visible at Collserola and at the hills of La Rovira. On top of this layer, loams, clays, gravels and calcareous blocks settle down.

    The upper side of the plain (very affected by the erosion of the torrents) drops smoothly and regularly from Collserola to the meeting point between Ciutat Vella and L’Eixample, where there is a considerable gap.

    The lower side goes down to the sea and it is made mainly of sedimentary materials coming from Collserola that were swept along by the rivers Besòs and Llobregat. That has moved constantly forward the coastline: in the 5 c. BC, at the South side, the coast was 5 km inside the current coast and the ancient Roman harbour, which was working during the reign of James I of Aragon, spread out from the hill of Les Falzies (currently, Pla del Palau) to sandy area of Santa Clara (now the Parliament, at Parc de la Ciutadella). In the 14th c. it was already blocked.

    As the land was gaining terrain to the sea, the coastline was varying. This way, the plain of Barcelona was formed and it is possible to say that Montjuïc contributed, because of its location, to retain the sediments and to consolidate the town’s big place.

    That plain’s climate is mild Mediterranean, because of its sheltered location, despite that in summer it is common the muggy weather. The rain is limited and is distributed unevenly throughout the year, with very intense downpours at the end of the summer and during autumn.

    The natural vegetation was a typically Mediterranean one: pines, oaks, undergrowth of heathers, Viburnum tinus, strawberry trees and climbing plants on the mountain and alders, poplars, reeds, rushes and deciduous trees on the plains and the humid hollows and riparian trees near the sources and the marshes. On the mountain range and the side facing to the sea, the forest was thicker, with darker oak forests. As time passes by, many of the terrains became pastures and farming lands (carobs, vines, orange trees, cereals and, near the torrents and the water points, vegetable gardens).

    Outstanding places

    Taber Mount (16,9 m), first focus of stable population

    Tibidabo (516.2 m), top of Collserola mountain range

    Montjuïc (184.8 m), hill over the harbour, main park and the lungs of the town Hills: Carmel (265.6 m), Rovira (206.8 m), Putxet (182.7 m), Peira (138 m), Monterols (127.3 m) 

    History and curiosities: 

    The gap where the upper and lower side of the plain meet, on the border between Ciutat Vella and L’Eixample, was in old times used to rest the town walls against it and for the mills and the pools of the tanners and weavers. As the land was gaining terrain to the sea, many of the coast lagoons, ponds and marshes disappeared, sometimes because of the direct human action, both in Middle Ages and in modern times.

    For further information: 

    AJUNTAMENT DE BARCELONA (ed.). Montjuïc, parc central. Barcelona, 2006

    ROCA, Estanislau. Montjuïc, la muntanya de la ciutat. Barcelona: Institut d’Estudis Catalans, 2000

    SOBREQUÉS I CALLICÓ, Jaume (dir.). Història de Barcelona (8 vol.). Barcelona: Enciclopèdia Catalana, 1991-1992