In this article we describe TM4L - an environment for building, maintaining, and using standards-based, ontology-aware e-learning repositories. It is based on the idea that concept-driven access to learning material implemented as a Topic Map can bridge the gap between a learner and targeted knowledge. One of the driving goals of this work is to increase the reusability of available educational resources by enabling the use of a developed subject ontology with courses on the same subject with different stricture. Another goal of TM4L is to support an efficient context-based retrieval of learning content tailored to the needs of a learner working on an educational task. The paper focuses on three aspects of the TM4L environment: domain modeling, editing capabilities and the interface for exploring the learning collection. The key features of the TM4L functionality are illustrated with some examples.