Peer-to-Peer systems allowing fast and easy search for information shared by the users of a communication network, are considered to have a huge impact on next generation mobile service platforms. To support applications that employ content categories or limit services to certain contexts more efficiently, we describe a hierarchical P2P system in this paper. In particular, our system introduces hierarchies in a DHT-based P2P system to allow topic-based queries. Based on the query statement, which is based on XPath, queries can traverse the hierarchy if the content is not found in one topic-space. Examples illustrate how our concept is used for file sharing and location-aware applications.