One way to solve the heterogeneity problem of distributed legacy databases consists in wrapping them as objects that can be queried for retrieval and updating. This paper presents the InterDB approach for the generation of conceptual wrappers for legacy databases. The generated wrapper is a software layer that offers a conceptual interface based on the conceptual schema of the wrapped database. The InterDB approach provides a complete methodology for conceptual schema recovery (through reverse engineering) and mapping building. The methodology is supported by the DB-MAIN CASE tool that helps generate the wrapper.