In this paper a system for storing and retrieving imaged multimedia documents by content is described. This system is being developed within the Esprit project STRETCH (STorage and RETrieval by Content of imaged documents). The core of STRETCH system is a powerful Archiving and Retrieval Engine, based on a structured document representation and capable of activating appropriate methods to characterise and automatically index heterogeneous documents with variable layout and subsequently retrieve them by answering to complex queries. The produced document base, or "Docu-base", relies on an object-oriented internal representation and related characterisation and search methods. A prototype was implemented and successfully tested, in particular, in the creation of an invoice archive.