Rapid advances in multimedia technology necessitate the development of a generic multimedia information system with a powerful retrieval engine for prototyping multimedia applications. We develop a content-based retrieval engine (CORE) that makes use of novel indexing techniques for multimedia object retrieval. We formalize the concepts related to multimedia information systems such as multimedia objects and content-based retrieval. We bring out the requirements and challenges of a multimedia information system. The architecture of CORE is described in detail along with the associated retrieval mechanisms and indexing techniques. Various modules developed for efficient retrieval are presented with some APIs. The efficacy of CORE is demonstrated in the development of two multimedia systems, a computer-aided facial image inference and retrieval (CAFIIR) system and a system for trademark archival and retrieval (STAR), which have been developed at the Institute of Systems Science (ISS). We expect that CORE will be useful for effective prototyping of other such multimedia applications.