The trend in agent-oriented software engineering is to consider multiagent systems (MASs) as a radically new way of engineering software. This position isolates agent-oriented software engineering from mainstream software engineering and could be one important reason why MASs are not widely adopted in industry yet.In this paper, we present another perspective on software engineering with MASs. We put forward MASs as software architecture. We give an overview of a reference architecture for situated MAS. This reference architecture extracts and generalizes common functions and structures from various applications we have studied and built. The reference architecture provides a blueprint for architectural design of MAS applications that share the come base of the systems it is derived from. Considering MASs essentially as software architecture paves the way to integration with mainstream software engineering.