Reverse engineering methods produce different descriptions of software architectures. In this work we analyze and define the task of exploring and comparing these descriptions. We present a novel visualization technique to compare architectures based on the decomposition of the software system and on the dependencies among the code entities. A case study related to software clustering shows how we can apply this technique in practice. Categories and Subject Descriptors H.5.m [Information Systems]: Information Interfaces and Presentation General Terms Design Keywords software architecture, hierarchy comparison, graph visualization Note. This paper makes heavy use of colors. Please read a colored version of this paper to better understand the ideas presented.