Architecture is about buildings, and consequently, reflecting philosophically on architecture comprises asking what buildings are. The question seems easy to answer using everyday concepts, refined, if necessary, by referring to concepts from civil engineering or building legislation. Philosophical interest is raised mainly when time enters into the problem. This paper argues that the identity of buildings through time cannot be reduced to the identity of their designations, their materials or their locations in space and time. Instead, it proposes to construe (...) buildings as Peircean sign processes. The identity of a building then becomes a function of the maintenance of sign relations by value-guided communities. (shrink)