 Despite its unassuming grey cover, this photo album in Cooper Hewitt's collection has an important story to share about the French architect Hector Guimard and the major changes happening in Paris around 1900. It contains 48 black and white photographs, some of which are shown here. They document the construction of a prototype house in Paris that still stands today. It was the only structure ever built using Guimard's standard construction system. Modest in size, traditional in form, and built from precast blocks that were formed with reusable molds, the prototype house depicted here is not the type of work we typically associate with Guimard. Guimard is better known for his upscale residences and his station entrances for the Paris Metro. As seen in this drawing, Guimard's designs for these well-known projects are dominated by the repeated use of sinuous expressive lines. Guimard's experiments with standardization and prefabrication in support of affordable housing were equally important to the development of his signature style and mark him as an architect of his time. Guimard described the turn of the century as a time of transition, trouble, and commotion. This was especially true of Paris, where streets were bustling with people and urban life as shown in this archival footage. In 1853, Napoleon III had commissioned politician Baron Georges Jean Hausmann to implement a radical new plan for Paris that would transform the maze-like medieval city into an easily controlled metropolis with wide boulevards, sanitation systems, and monumental buildings and parks. But the changes orchestrated by Hausmann had disastrous repercussions for the working class. Their living quarters were demolished to make room for apartments for the new middle class, who sought city living with modern amenities. Rents in central Paris soared and working class people were displaced to the city outskirts. Guimard was among many turn of the century architects who recognized the potential of modular building systems to improve living conditions for the working poor and to rebuild the devastated regions of France following World War I. Guimard began experimenting with standardized construction techniques as early as 1900, as evident in the modular design system he created for the Paris Metro. He designed prefabricated cast iron components, including guardrails, medallions, and lamp posts using his signature, curving lines. These components could be produced and configured to suit different sites. Guimard began to apply the same concepts of modularity to the design of affordable housing. These photographs document the fabrication of modular cast-dome blocks according to Guimard's system of standard construction. Between December 1920 and January 1921, Guimard applied for at least 10 patents related to standard construction. His innovations included a system of wooden guides and templates, as well as new truss, flooring, and gutter systems. The photographs shown here document the application of these innovations on the job site. But the major innovation of standard construction was Guimard's design for a series of interchangeable, interlocking cast-dome blocks of various shapes and sizes that could be laid up without mortar. Instead, the hollow blocks were joined together with poured concrete and iron rods, which made the entire assembly structurally sound. Used with linear grooves and curving designs, the prefabricated blocks recall Guimard's earlier modular units for the Paris Metro. Both systems represent Guimard's efforts to marry traditional craftsmanship with new materials and cutting-edge fabrication methods. As shown in these recent photographs, Guimard's embrace of totally integrated design is still evident in the carefully crafted stone and iron details integrated with the facade of the prototype house. Guimard had hoped that his standard construction system would revolutionize the construction industry. But like many standardized systems invented during the interwar period, standard construction was forgotten in a flurry of post-war construction. Over a century after its design, standard construction's guiding principles and values resonate with continuing efforts around the world to build affordable, well-designed housing for all.