|Abstract:||While current search engines serve known-item search such as homepage finding very well, they generally cannot support exploratory search effectively. In exploratory search, users do not know their information needs precisely and also often lack the needed knowledge to formulate effective queries, thus querying alone, as supported by the current search engines, is insufficient, and browsing into related information would be very useful. In this paper, we present a formal navigation-based retrieval framework to unify querying and browsing and treat both as navigation over topic regions. To support browsing effectively, we treat search logs as "footprints" left by previous users in the information space and build a multi-resolution topic map to guide a user in navigating in the information space. To test the effectiveness of the proposed methods, we build a prototype system based on a small sample of search logs and a commercial search engine. Our experiment results show that the proposed navigation-based framework is promising and the proposed methods for guided navigation are effective.