Urban theory has traditionally characterized the city as a whole that is composed of parts. In this essay, I argue that this relationship is challenged in the context of an “Historic City” — a relationship we understand through the concept of interdetails. This research is focused on Barcelona and the work of Ildefons Cerdà (1815-1876) — the engineer responsible for the urban extension known as Eixample (1859) and the first scholar who faced the challenge of defining the Historic City in relation to a new one. Central to this discussion is the tile vault, also named Catalan vault. While the origin of the vault can be traced to the XV century in Catalunya, it was used extensively in the construction of Barcelona and is essential to understanding the identity of the place. I consider the practices and processes related to construction, their evolution, and the conservation of the Catalan vault in thirty-three of the most significant heritage buildings in the Raval district. In 1980, Lluís Clotet proposed a renovation of this area with the urban plan “From Liceu to Seminari,” as the final episode of Cerdà’s original proposal. The novelty of Clotet’s design was to revitalize the area by connecting and conserving the existing heritage buildings by introducing new uses. However, Clotet missed the opportunity to explore the tangible and intangible dimension of traditional details in relation to the Historic City as a whole. Rather than celebrate historic details, this intervention generated demolition or concealment under new materials and processes like reinforced concrete. The argument is that this transformation affected our understanding of Barcelona — not only at the scale of architectural details like the Catalan vault — but at the scale of the Historic City as a whole. I conclude by proposing that the “construction and construing” of the Catalan vault is an interdetail that is integral to fully understanding the Historic City,¹ and that we must reconsider how currently historic urban conservation is understood by posing the possibility that the Historic City may best be conceptualized as a whole contained in the part.

Keywords: historic city, urban conservation, detail·building·city, interdetails

¹ Marco Frascari uses this expression to describe the tangible and intangible characteristics in the generation of architectural details. See Marco Frascari, “The Tell-The-Tale Detail” in K. Nesbitt, editor, Theorizing a New Agenda for Architecture, (New York: Princeton Architectural Press, 1996), 498.