This paper presents a novel technique for exploring and navigating large hierarchies, not restricted to trees but to directed acyclic graphs (DAGs). The technique combines two different visualizations emphasizing different points of view the user can adopt when analyzing the content of the hierarchy. Usual hierarchical (node-link) layout reflect the relative position of nodes in the hierarchy while a variation of a treemap emphasizes node attributes. The classical treemap algorithm has been adapted in order to deal with DAGs. Linking the two views enables the user to visually and interactively explore elements of the hierarchy with respect to selected attributes, while being able to locate the node in the DAG.