My friend Barbara asks: “How would you archive mobile buildings? Buildings that (dis)assemble like Legos…” She is referring to the work of Alberto Mozó, an architect based in Santiago, Chile. Mozó has the idea that pre-fab mobile architecture–buildings which can be assembled and disassembled with ease, or the parts re-purposed at will–has great value for Architecture and Urbanism today. The architect’s statement about the office building pictured above introduces the theme of “Transitividad” or transitivity to describe the quality of in-betweeness, or openness to disassembly, that the building embodies. To get back to Barbara’s question, if the building embodies transitivity then how could it be archived? Well my first suggestion is that the method of archiving, the archival practice, must also have a transitive quality.