How can architecture be kept, depicted and read in records? What can architectural historians find when they turn to archives? What is their evidence, and what could it be? This article is about the importance of archives as an operative tool for architecture, its history and its practice; about the many ways in which archives can be profited from, tested and explored by architectural historians in their work; and about the web of research threads archives offer historians, the meanings they convey and hide, and the problems and solutions they pose. These are reflections based largely on personal experience, and they imply a statement as to what architectural history and archives might expect of each other. The Portuguese case is explored: the country's archival sources for architectural history of the contemporary period are detailed, and a provisional classification is proposed.