The transformational models of these much smaller cities represent, on the one hand in the case of Vienna, a relatively unique way of changing the city's form by using the space of its redundant walls, versus, in the case of Barcelona, a much more common way of expanding the city by appropriating and sub-dividing open land outside the city's core.
As European cities were located toward the east, so they required larger fortification. Vienna, for long a bastion against the Ottoman threat, having lost the rationale for its walls and their surrounding glacis, found in this space the place to build for its newly empowered middle class. The old city was dominated by religion and royalty; for the new liberals, these had no role in the new city which was to be their "political bastion, economic capital and radiating center for their intellectual life." The Ringstrasse satisfied this ambition as it encircled the old city from the Danube with continuous regions of activity: warehouses and offices close to the water, a financial center, the university, the parliament/town hall/justice/president's palace complex, a museum district, a music zone, followed by apartments back to the river. The Ringstrasse was not intended to bridge to the outer city; it was a great avenue in itself made up of items which "carry the citizen from one building to another, as from one aspect of life to another." As if a new architecture of the middle class was impossible, its public architecture represented itself through appropriate choices from the past, Gothic for the free commune of the Town Hall, Baroque for the aesthetic enthusiasm of the Theater, Renaissance for the enlightened culture of the University, and Greek for the democracy of the Parliament. Apartments were built as large multi-family dwellings, gruppenzinhaus, modeled on aristocratic palaces with rusticated ground floor for shops. Like elsewhere, upgrading the city's appearance went hand-in-hand with technical improvements, such as channeling the Danube, devising an urban train system and building the first city hospital. Some have linked the massive real estate speculation with an increase in the appalling housing conditions of the poor leading to the socialist victory of "red Vienna" and the invention of a new housing type, the hof, pugnacious housing enclaves demonstrating the workers' presence in the city. The Vienna story, beyond including one of the greatest periods of cultural achievement ever, sets up the contrasting theories of urban "goodness" between Camillo Sitte on the one hand, the champion of craft and Wagnerian gesamtkunstwerk, and small-scale, picturesque urban morphologies, versus the great architect and urbanist, Otto Wagner, who saw the modern city as efficient, expansive, and open-ended, served beneficially by modern technology.
Barcelona was a walled medieval city and the center of industrial development in Catalonia. But its overcrowded condition—about the same number of people died of cholera in the 1830's as in Paris—demanded expansion which came in the form of a competition won in 1853 by the city's architect. Invalidated by royal decree, the expansion plan fell to the engineer, Cerdà, whose plan was built soon after. The plan was seen as a rational structure of grid elements 113 meters square governed by ordenanzas and trazado in a pattern extending outwards from the old city. The corners of each block was cut at a 45-degree angle to create small squares between blocks, and each block had an open center presumably to be used as open space for the residents but taken over and used in many different ways over time. A major avenue, the Passeig de Gràcia, linked from the old Ramblas to the hills, and a wide diagonal highway was meant as a by-pass for traffic attempting to pass through the city. The Ensanche, as the Cerdà-designed area has come to be known, is highly regarded as an urban structure built on vacant ground and as well articulated as if it were architecture. It has served as host to the buildings of Gaudi, for the Casa Mila apartment block which makes full use of the diagonal corner as a façade, and for the formidable Sagrada Familia. In 1932 it was subject to a new "modernist" plan by Le Corbusier and GATCPAC, and in recent years it has been subject to various changes, those brought about by civic repair and those engendered by the demands of the 1992 Olympic Games. Cerdà's plan is one variation on a theme of urban expansion outward from a historic center that occurs frequently in nineteenth-century European plans such as Kleanthes-Schaubert's plan for Athens (1833), Antonelli's plan for Turin (1852), Castro's plan for Madrid (1860) and Trotti's plan for Bari (1867). It is also the preferred mode for the expansion of smaller towns all over Europe.
Fig. 1 and 2 from Aibar, Eduardo, and Wiebe E. Bijker. "The Cerdà Plan for the Extension of Barcelona." Science, Technology, & Human Values 22, no. 1 (1997): 3–30.
Gruppenzinshaus, Danube Canal, Karlsplatz Stadtbahn Station, and Karl Marx-Hof (Vienna, Austria), proposed plan for Vienna (Camilo Sitte), zoning of expansion and extension for Vienna (Otto Wagner), plan of Ensanche in Barcelona, Spain (Ildefons Cerdà), Las Ramblas, and Passeig de Gràcia (Spain); Casa Batlló, Casa Milà, and La Sagrada Familia (Antonio Gaudí); proposed plans for Barcelona (Le Corbusier); proposed plans for Barcelona (Leon Krier); plan for Torino (Alessandro Antonelli); plan for Madrid (Carlos María de Castro); plan for Bari (Trotti); plan for Athens (Kleanthes-Schaubert); Altamura, Puglia (Italy)