Software architecture is a critical artefact in the software lifecycle. It is a system blueprint for construction, it aids in planning teaming and division of work, and it aids in reasoning about system properties. But architecture documentation is seldom created and, even when it is initially created, it is seldom maintained. For these reasons organisations often feel the need to recover legacy architectures, for example, as part of planning for evolution or cloud migration. But there is no existing general architecture recovery approach nor tool that can be applied to any type of system, under any condition. We will show that one way of achieving such generality is to apply systematic code inspection following a Grounded Theory (GT) approach. Though relatively costly and human-intensive, a GT-based approach has several merits, for example: (a) it is general by design; (b) it can be partially automated; (c) it yields evidence-based results rooted of the system being examined. This article presents one theoretical formulation of a general architecture recovery method–called REM–and reports on the evaluation of REM in the context of a large architecture recovery campaign performed for the European Space Agency. Our results illustrate some intriguing properties and opportunities of GT-based architecture recovery approaches and point out lessons learned and venues for further research.