When designing for a group of professionals, it is important to know their work practice. This is well-known and practised, e.g., in agile software development in which customers are involved in development work, but less so when the professionals are software engineers or in particular software architects. In the SA@Work project, we have extensively studied software architect work at four Danish companies using both qualitative and quantitative approaches. In this paper, we report on concerns (analysis, design, evaluation, realization, management, and interaction) that software architects have in their work. Our lessons learnt are software architecture work (in the setting that we studied) is as much about non-technical as technical work, that architecture is often found "in the small" and that architects vary widely in type. Furthermore, we point to lessons for future research and development of software architecture techniques.