At the onset of the First World War, European countries suffered a sudden but anticipated setback that also affected their artistic and, therefore, architectural production. Arts & Crafts in Great Britain, Art Nouveau in French-speaking countries, the Wiener Sezession in the Austro-Hungarian area, Modernismo Catalan in Spain and Liberty in Italy, all revisited the theme of Nature as an artifice to be used in architecture and in designing human spaces. As early as the first decade of the 20th century, ideas that took inspiration from rational geometric principles challenged this approach to composition.

28 July 1914 is the date that conventionally marks the start of 20th-century events and the definitive break with the 19th century.
Indeed, for almost a decade, certain cultural milieus had already been challenging the identity of the positive century and had started embracing the innovations and momentum of the new century. One of these was the architectural milieu, which experienced a period of transition between abandoning the compositional, distributive and structural system and adopting new thinking and new technologies. This time frame, with its cultural exchanges, research and remarkable scientific and social achievements, was also known as the Belle Epoque.

One of the many effects of the Second Industrial Revolution was that it drew a considerable number of workers, and consequently their families, to areas around major industrial cities. The relocation of such a substantial mass of population challenged the urban systems of large industrial cities like London and Liverpool in England, as well as Cologne, Dortmund and Düsseldorf in the Ruhr areas of Germany. The almost sudden emergence of working-class neighbourhoods forced these cities’ administrations to seek new solutions to provide minimum levels of public sanitation and health.
Many large European cities developed new organisational structures and implemented urban interventions that had a substantial impact on their areas. First, among all the big cities, from 1852 to 1870 (and beyond) Paris acquired a new infrastructural network with the Boulevard system designed by prefect George Haussman. Other European cities followed, including Barcelona in 1859 with Ildefonso Cerdà’s city plan, and Vienna that same year under the guidance of a group of architects that included Löhr, Stache, Forster, Van der Null and Von Siccardsburg.
Moreover, at the turn of the 20th century in Great Britain, several entrepreneurs integrated the urban demands of industrial production with the advancement of better social conditions. They invested in designing and building new cities in which industrial production could coexist with models and living spaces on a human scale. The garden cities of Letchworth and Hampstead were constructed in 1903 under the supervision of Ebenezer Howard, followed by Welwyn in 1919; they were to become benchmarks for many other projects in Germany, France and Italy.
Housing models were also investigated during the Belle Epoque period. Both compositional schemes and the layout of interior spaces experienced transformations that subsequently produced the most significant housing solutions we still find in present-day residential uses.

Back in 1859 the Red House, designed by William Morris, had already revolutionised a housing system that was based on old forms of use and had redesigned functional spaces that previously had been marginalised to poorly functional areas.
Functional spaces like the kitchen and bathroom occupied an important, albeit not essential role in domestic life and therefore were recognised to be on a par with other spaces having residential uses.

Moreover, in the second half of the 19th century, new technological solutions reached Europe after having been tested in the United States. When electricity was first used in building projects, Werner Von Siemens combined a hydraulic thrust system with an electrically driven system and designed the first elevator in Germany in 1880. This innovation further transformed the use and composition of residential and non-residential architectural spaces.
At the same time, to optimise the energy production needed to manage buildings, new installation projects were explored leading to the creation of centralised facilities for entire buildings.
William Morris’s insights, which other professionals had revisited for over fifty years, highlighted a crucial relationship in architectural composition: the relationship between the form of a building and its function. During the 20th century, this relationship would lead to the rise of different schools of thought, each marked by a greater or lesser emphasis on one or the other of these two elements.

The twenty-year period between the 19th and 20th centuries embraced this legacy and its challenges. By favouring form over function, Hector Guimard from France and Victor Horta and Henry Van de Velde from Belgium reinvented forms and structures inspired by the plant kingdom in composing spaces, volumes, structures and objects.
Stylised plant elements thus became slender and daring iron columns supporting the ramps of arches or flights of stairs, as in the Brussels buildings designed by Victor Horta on Rue Turin in 1893 or on Avenue Palmerston in 1895.
The experience of Art Nouveau in Belgium featured the linearity and dynamism of natural elements and typical natural movements. Walter Crane represented this with the apotheosis of the curved “whiplash” line that he used as his expressive medium. This was followed by the ideas of Henry Van de Velde, who added a psychological dimension to his celebration of the expressiveness of the line: the seamlessness of a line provides an understanding and an expression of the character of the person who generates it.
The combination of this poetic approach and technological progress also led to remarkable structural proposals such as Victor Horta’s 1896 project for the large common room of the Maison du Peuple in Brussels, which he crowned with a roof supported by a bolted iron structure. In 1904 Otto Wagner faced the same challenge and used cleaner lines in designing the central hall of the Post Office Palace in Vienna, which he covered with a structure of steel and glass.

In keeping with this concept of reinterpretation, Joseph Hoffmann released architectural elements from their long consolidated compositional cage and celebrated them for their specific features, as can be seen in the organisation of the 1905 Stoclet Palace façade in Brussels, where the windows became a compositional element extending beyond the layout of the façade and connecting with the roof.
The Belle Epoque time frame also includes the period in which structural elements, conceived initially solely as functional components, acquired their expressive distinctiveness and came to possess decorative features. From Paxton’s Crystal Palace in London in 1851 to Henry Labrouste’s National Library in Paris in 1862 and Gustave Eiffel’s construction of the Tour for the Universal Exhibition in Paris in 1889, materials like iron and glass were frequently employed with increasingly innovative technical solutions.

While these technological innovations were under development, several French experiments led to the earliest instances of civil constructions using reinforced concrete structures. The achievements of two engineers, Coignet in 1861 and Monnier in 1869-1875, were soon integrated into the work of Auguste Perret, thus launching a fundamental building technique that was to be used for architectural and engineering production throughout the following century.
The flexibility and plastic properties of this construction technique that was patented in its many forms in several European countries, provided one of the main opportunities for initiating change at a time when attention was being paid to form and its relationship with the function of a space.

The Austro-Hungarian architect Adolf Loos was the driving force behind this critical period during which function was favoured over form. In 1908 he published his essay “Ornament and Crime”, which banned superfluous ornamentation and promoted pure geometry and the freedom of volumes.
His ideas were both nihilistic and generative and gained the support of other critics of the period who, at the turn of the century, exposed the depletion of the original premises of an entire era. While one of the hallmarks of the Belle Epoque had focused on improving social conditions in urban centres, the results at the beginning of the century showed how inadequate the outcome had been. The great technological innovations had produced remarkable results and created large urban systems, but they also had critical implications for the identity of individual citizens.
Against this social backdrop, which was increasingly focused on the urban presence of industry, the role of craftsmen, who until then had been vital in architectural projects, inevitably had to take new serial production methods into account. The interaction between “industry” and “crafts”, particularly in the field of architecture, became one of the main issues of the debate about compositional research and formed the basis for the appearance of new currents of thought that became essential for the cultural, artistic and architectural dynamics of the first half of the 20th century.

The social debate about the evolution of industrial society was the cornerstone of cultural movements such as “De Stijl”. The purpose of their projects was to provide suitable housing solutions for broad social groups while at the same time respecting individual identities and improving their original conditions.
Theo Van Doesburg, a painter, writer and architect, signed the first Manifesto of the movement together with other intellectuals that included the painter Piet Mondrian and the architect Jacobus Johannes Pieter Oud. The “De Stijl” magazine, which appeared in October 1917, was the preferred channel of communication for the dissemination of their ideas.
This new direction was developed in opposition to the decorative excesses of Art Nouveau and was based on the legacy of the avant-garde movements of the period, which simplified forms, reduced volumes and abandoned perspective. Absolute rationality and formal purity were seen as the fundamental principles of design. In the same spirit as Piet Mondrian’s compositional ideas, chromaticism also played a role in architecture: anything colourless had to correspond to a void, while coloured elements conveyed fullness and function.

This is evident in the movement’s architectural masterpiece, Schröder-huis in Utrecht, which Gerrit Rietveld designed in 1924. It is a perfect synthesis of the movement’s theories: the furnishings and the architectural structure share the same construction principles. The house is on two levels and whatever is shape and structure is white. The floors that mark the interaction between interior and exterior are grey, while primary colours, combined with white, grey and black, highlight all the linear elements such as lintels, pillars and downpipes. Lastly, architectural features such as doorways, windows and railings, are black and white.
The house itself was fairly small and was designed as a residential model for an extended social class. The interior featured structural elements and movable walls to provide for different functions and activities.