  Software engineers need relevant and up-to-date architectural knowledge (AK),
in order to make well-founded design decisions. However, finding such AK is
quite challenging. One pragmatic approach is to search for AK on the web using
traditional search engines (e.g. Google); this is common practice among
software engineers. Still, we know very little about what AK is retrieved, from
where, and how useful it is. In this paper, we conduct an empirical study with
53 software engineers, who used Google to make design decisions using the
Attribute-Driven-Design method. Based on how the subjects assessed the nature
and relevance of the retrieved results, we determined how effective web search
engines are to find relevant architectural information. Moreover, we identified
the different sources of AK on the web and their associated AK concepts.
