Program comprehension during software maintenance is a difficult task, hence the need to support it by recovering the as-built architecture of the system to be maintained. In this paper, we propose a method to recover runtime architecture models of object-oriented systems. The method combines static and dynamic analysis to recover an Object Graph (OG) which includes information that will be used to manage the complexity of this graph. In addition, composition/ownership relations between objects are exploited to embed composite structures into the OG nodes. This enables to support a hierarchical visualization of the recovered architecture. We implemented a prototype of the method and experimented it on a case study. The results of this experimentation are promising.