Barcelona Eixample Case Study: Cerdà's Grid, Chamfered Blocks and Superblocks (Ildefons Cerdà)

The Eixample is the grid of chamfered square blocks that Ildefons Cerdà planned in 1859 to extend Barcelona beyond its walls. Its module is simple: streets 20 m wide, blocks 113 m a side, and every corner cut at 45° so that each crossing opens into an octagon. This case study explains the plan, what Cerdà meant the blocks to be, what was built, and how the city's superilla (superblock) programme is reworking the same grid.

Where to see the real plans. Cerdà's maps and drawings are in the Llegat Cerdà at the Arxiu Històric de la Ciutat de Barcelona, and the University of Barcelona shows the 1859 plan from that archive on its Cerdà Plan page. The diagrams below are MOA's own schematics. Our guide on how to do an architecture case study shows how to turn sources like these into sheets.

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The brief and who planned it

Barcelona's walls came down between 1854 and 1856 (López Guallar, Arxiu Municipal), though the army resisted building on the military zone around them until December 1858. Cerdà did not wait for a brief. On the civil governor's commission, his survey of the plain began on 18 December 1854 and went on through a winter of heavy snow, and he thought of the extension as unlimited: a grid that could grow wherever the ground allowed, with no new walls (Ramon Grau, in the city archive's studies of Barcelona's cartography).

Approval was a contest between Madrid and the city. The council called its own competition in 1859, but the Ministry of Public Works approved Cerdà's project by Royal Order of 7 June 1859. On 19 October the council's jury chose, unanimously, the plan of the architect Antoni Rovira i Trias; the government confirmed Cerdà's in May 1860 (Glòria Santa-Maria Batlló, Decidir la ciutat futura. Barcelona 1859, MUHBA). Enciclopèdia Catalana dates the first decree 7 August 1859; we follow the MUHBA study, which prints the June order.

Site and context

The plain runs inland from the sea between the valleys of the Llobregat and the Besòs. In 1859 it held farmland and separate towns such as Gràcia and Sant Martí de Provençals, so the plan crossed several municipalities: in the words of Miquel Corominas and co-authors, Barcelona's first metropolitan plan (Corominas, Moreno and Corominas, 2023). The ground shaped the result. The central Eixample, on dry, low-value farmland, filled with flats over workshops. In Poblenou, on irrigated land cut off by railways, owners pulled up the stakes marking the street crossings, and the blocks filled instead with low industrial sheds.

Barcelona Eixample Cerdà 1859: the plan idea

Cerdà was a theorist as well as a planner; his Teoría general de la urbanización appeared in 1867 (Enciclopèdia Catalana). Enciclopèdia Catalana sums up the plan: social facilities spread over an open street network, low densities, blocks built on only two sides or in an L, no single centre, and no spaces set aside for political power. Three ideas carry it:

• Equality. The same street and block everywhere, so the edge got the same conditions as the centre (Corominas et al. 2023).
• Hygiene. A target of 40 m² of city per inhabitant, set after studying the plots and density of the old city (Miquel Corominas, "Cerdà, geómetra", 1999).
• Movement. Streets wide enough for future traffic, when Barcelona's widest street was no more than 18 m.

Barcelona Eixample grid: block, street and chamfer

Corominas (1999) reconstructs the numbers. Cerdà's 1855 draft asked for streets at least 35 m wide; the 1859 project graded them at 20 m for light traffic, 30 m for ordinary and 50 m for heavy. Comparing other grids, among them Buenos Aires at 116 m, he chose a square block of 113 m, the smallest size he tested. It covers 12,432 m², and street plus block puts a street axis every 133 m.

Each corner is cut to a chamfer (xamfrà) face of 20 m. The Marquis of Salamanca asked for them to be reduced to Madrid's 4 m, and complained that the Diagonal was too wide; the council refused. In section, Cerdà matched building height to street width, about 20 m on a 20 m street. Later owners added floors by lowering storey heights, so cornices reached only about 24.40 m, roof storeys apart.

What Cerdà intended for the blocks

In the 1859 model a block was built on two opposite sides, with a garden between: of its 12,432 m², 4,131 m² were plots and 8,301 m² garden, about two to one. The smallest building unit was 20 m by 20 m, and Cerdà put the deepest acceptable building at 28 m (Corominas 1999).

Barcelona Eixample plan: how it was built and governed

Cerdà could not secure the gardens in law, because land could then be expropriated only for roads and railways. His revised plan of 1861 was therefore a plan of street alignments, with no open spaces, facilities or building rules, which in effect accepted building on all four sides. It also moved the grid 30 m to meet the existing Passeig de Gràcia, widened from 40 m to 60 m (Corominas et al. 2023). The civil governor oversaw the extension until the first Junta d'Eixample in 1865, and Cerdà did the technical work until then; each town on the plain kept its own building ordinances.

Owners built what paid. Between 1860 and 1953 they chose freely between flats and fully industrial buildings. In the central Eixample the result was a closed ring 25 to 30 m deep, mostly five to seven floors, around a courtyard more than 50 m across, with workshops and stores on the ground floor across the whole block; for years, Corominas et al. write, it was the largest industrial area in Spain.

What changed: closed blocks, lost courtyards and their return

Ordinances kept raising the limits, to 73.6% of the block and a depth of 28 m in the rules in force from 1942 to 1976. Corominas (1999) argues that the real loss was not density but flats that lost one of their two facades, and courtyards built over so that no trees could grow. The 1986 Ordinance for the Rehabilitation and Improvement of the Eixample reserved a green court inside the block.

From 1987 the city began recovering block interiors as public gardens. The district lists 45 open, three more coming and seven recovered since 2015, among them the gardens of the Torre de les Aigües water tower, with the goal of a green space within 200 m of every home (Districte de l'Eixample, Interiors d'illa).

Barcelona Eixample population density

In a 48-block study area of the central Eixample, Corominas et al. (2023) counted 18,239 residents: 320 inhabitants and 134 dwellings per hectare, gross, with a net built ratio of 4.67 m² of floor per m² of plot. That is roughly an FSI of 4.7 with no towers; our explainer on carpet area, built-up area and FSI covers how India counts the ratio.

The superilles programme today

A superilla groups several blocks, keeps through traffic on the streets around them and gives the streets inside to people. Barcelona first tried it in Poblenou, Horta and Sant Antoni (Ajuntament de Barcelona, Superilles); in Sant Antoni the work recovered 23,709 m² for pedestrians (Superilla de Sant Antoni).

In January 2021 the city scaled it up as Superilla Barcelona, with the Cerdà grid first, citing nitrogen dioxide averaging 50 µg/m³ in 2019 against the WHO figure of 40 it quoted, and heavy through traffic (Superblock Barcelona, 2021). The plan is 21 green axes over 33 km and 21 squares of 3.9 ha, with a square or axis within 200 m of every resident (Superilles, Eixample). The chamfers make the squares possible: where two axes cross, the octagon of four cut corners, about 2,000 m², becomes a square. The green-axis model document notes that private vehicles make 26% of trips but take about half the street space used for movement (Model d'Eix Verd).

The first green axes

The first phase covers parts of Consell de Cent, Rocafort, Comte Borrell and Girona, with squares where Consell de Cent meets Rocafort, Comte Borrell, Enric Granados and Girona, chosen through competitions that drew 40 and 46 entries (Resolució dels concursos). The city describes the result (Així seran les noves places i eixos verds; El carrer del segle XXI):

• one level from facade to facade, kerbs removed, pedestrians first
• vehicles at 10 km/h, made to turn at the corners instead of driving through
• asphalt replaced by panot paving tiles and granite
• greenery up from 1% of street area to an average of 14%, with 438 new trees

Reception and criticism

The plan. In 1901 the promoters of Léon Jaussely's plan for linking the Eixample to the surrounding towns attacked Cerdà's grid on aesthetic grounds; Enric Prat de la Riba faulted it for leaving no political spaces, and Josep Puig i Cadafalch was harsher, though mostly about the Eixample as built. The architects of GATCPAC began its re-evaluation on functional grounds (Enciclopèdia Catalana). Corominas (1999) argues that the 20 m street and 133 m spacing have absorbed about 150 years of change.

The superilles. A modelling study by ISGlobal, BCNecologia and others estimated that 503 superblocks across Barcelona could prevent 667 premature deaths a year, an estimate rather than a measured result (Mueller et al., Environment International, 2020). A UAB survey of 1,211 Eixample residents in October 2023 found 66% felt the pacified streets had affected them positively and 20% negatively; on the new axes the top complaint was too much noise and street life (TRANSEQUI, UAB).

The courts. In September 2023 a Barcelona court annulled the Consell de Cent axis between Casanova and Bruc, including the Enric Granados square, because it needed an amendment to the Metropolitan General Plan (PGM). The High Court of Justice of Catalonia upheld that in March 2025, with one dissent (CGPJ, 19 March 2025), and the council said it would appeal to the Supreme Court (Ara, 18 March 2025). Lower courts also ruled against sections of Rocafort and Comte Borrell (Betevé, 23 May 2024). We found no Supreme Court decision as of November 2026.

The politics. As a candidate in March 2023, Jaume Collboni called reopening 30 block interiors, at €171 million over two terms, more viable than more green axes (Betevé, 22 March 2023). As mayor, his government said in 2024 it would fix axes where parked cars and vans had broken planter guards and irrigation cost more, and began redesigning the Sant Antoni streets, about 13,400 m² for around €8 million, from early 2026 (Betevé, 23 May 2024).

Lessons for Indian cities

This is our reading, not a rule from any Indian authority.

1. Fix the street and block module before the plots. Cerdà chose the 20 m street and 113 m block together, from density and traffic, and the grid has since taken new uses without demolition. In an Indian layout or town planning scheme, testing block size against walking distance at the start is cheap; widening streets later is not.
2. Give corners room. Salamanca wanted the chamfers cut to 4 m. They now give sight lines, turning space and, in the superilla plan, a square at each crossing of two axes. A splayed corner reserved at the plotting stage keeps that option open.
3. Protect open space at block level. Cerdà's gardens vanished because limits were set plot by plot and ground floors could fill the courtyard, and Barcelona is still buying space back. Our guide to setbacks, FAR and height limits shows how Indian byelaws work plot by plot; a shared court fixed for the whole block is a stronger tool.
4. Amend the plan before the paving. Consell de Cent was built and then annulled because the street's function changed without a PGM amendment. WRI India notes that India's 2017 TOD policy likewise depends on cities writing special development control regulations and local area plans (WRI India, 2017).

The Eixample makes a good thesis comparison with Chandigarh's sectors or a Gujarat town planning scheme; see our B.Arch thesis topics by typology. Our Brasília, Canberra and Haussmann's Paris case studies, coming in this series, cover other planned cities.

Visiting the Eixample

• Streets. To see the module, walk any street between two chamfered crossings; to see the change, walk the Consell de Cent green axis and the Sant Antoni streets around the market.
• Block interiors. The district's interiors d'illa map lists the recovered courtyard gardens by neighbourhood.
• The drawings. Researchers can consult the Llegat Cerdà at the Arxiu Històric de la Ciutat de Barcelona.

Planning a layout, campus or housing scheme and want someone who thinks at block scale? Find an architect on MOA.

FAQ

What does Eixample mean in Barcelona?

Eixample is Catalan for extension (Ensanche in Spanish). It names both Cerdà's 1859 plan to extend Barcelona beyond its walls and the district built on it.

Who designed the Barcelona Eixample and when?

The civil engineer Ildefons Cerdà. He began surveying the plain in December 1854, the Spanish government approved his plan by Royal Order in June 1859 and confirmed it in May 1860, and building went on from the 1860s into the 20th century.

How big are the blocks in the Barcelona Eixample grid?

Each block is 113 m a side with 45° chamfered corners, about 12,432 m², and streets are 20 m wide, so street axes are 133 m apart. Cerdà graded streets at 20, 30 and 50 m, and widened Passeig de Gràcia to 60 m.

Why are the corners of Eixample blocks cut off?

The 20 m chamfers give drivers sight lines and room to turn, and turn each crossing into an octagonal space. The superilla programme uses those spaces to make squares of about 2,000 m² where two green axes meet.

What is the population density of the Barcelona Eixample?

In a 48-block study area of the central Eixample, Corominas and colleagues measured 320 inhabitants and 134 dwellings per hectare, with a net built ratio of 4.67, mostly in five- to seven-storey perimeter blocks.

Sources

• Corominas, M., Moreno, J. and Corominas, J.: L'Eixample de Barcelona: un pla, dues realitats, Documents d'Anàlisi Geogràfica 69/3 (2023), pp. 539 to 562 (accessed 11 Nov 2026)
• Corominas i Ayala, M.: Cerdà, geómetra, Ciudad y Territorio Estudios Territoriales XXXI (119 to 120), 1999, pp. 209 to 220 (accessed 11 Nov 2026)
• Arxiu Municipal de Barcelona: Estudis sobre la cartografia de Barcelona del segle XVIII al XXI, including Ramon Grau, "Conèixer per transformar. L'empresa cartogràfica d'Ildefons Cerdà, 1854-1865" (accessed 11 Nov 2026)
• Arxiu Municipal de Barcelona: Marina López Guallar, Barcelona després de Cerdà (accessed 11 Nov 2026)
• Arxiu Històric de la Ciutat de Barcelona: home page (accessed 11 Nov 2026)
• MUHBA, Ajuntament de Barcelona: Glòria Santa-Maria Batlló, Decidir la ciutat futura. Barcelona 1859 (accessed 11 Nov 2026)
• Enciclopèdia Catalana: pla Cerdà (accessed 11 Nov 2026)
• Enciclopèdia Catalana: Ildefons Cerdà i Sunyer (accessed 11 Nov 2026)
• Universitat de Barcelona: The Cerdà Plan (accessed 11 Nov 2026)
• Districte de l'Eixample, Ajuntament de Barcelona: Interiors d'illa (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Superilles (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Superilles, Eixample (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Superblock Barcelona: towards the city we want, January 2021 (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Model Nous Eixos Verds, B67 Palomeras Arquitectes and Cierto Estudio (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Així seran les noves places i eixos verds de l'Eixample (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Així serà el carrer del segle XXI (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Resolució dels concursos d'idees de Superilla Barcelona (accessed 11 Nov 2026)
• Ajuntament de Barcelona: Superilla de Sant Antoni (accessed 11 Nov 2026)
• Consejo General del Poder Judicial: El TSJ de Cataluña confirma la sentencia contra el eje verde de la calle Consell de Cent, 19 March 2025 (accessed 11 Nov 2026)
• Ara, Pere Virgili and Gerard Pruna: Setback for the High Court of Justice in Barcelona City Council, 18 March 2025 (accessed 11 Nov 2026)
• Betevé, Marc Garcia: Collboni diu que recuperar interiors d'illa a l'Eixample és més viable que fer eixos verds, 22 March 2023 (accessed 11 Nov 2026)
• Betevé, Roger Torres i Liñán: Collboni gira full als eixos verds de Colau, començant per la superilla de Sant Antoni, 23 May 2024 (accessed 11 Nov 2026)
• Mueller, N. et al.: Changing the urban design of cities for health: The superblock model, Environment International 134 (2020), 105132, via PubMed (accessed 11 Nov 2026)
• Universitat Autònoma de Barcelona, TRANSEQUI: Enquesta a residents: valoració dels carrers pacificats de l'Eixample, October 2023 (accessed 11 Nov 2026)
• WRI India, Prerna Vijaykumar Mehta and Merlyn Mathew: Ratification of the National TOD Policy and its implication for Indian cities, 1 August 2017 (accessed 11 Nov 2026)
• Wikimedia Commons: Copyright rules by territory: Spain (freedom of panorama) (accessed 11 Nov 2026)