This paper presents lessons learned from an experiment to reverse engineer a program. A reverse engineering process was used as part of a project to develop an Ada implementation of a Fortran program and upgrade the existing documentation. To accomplish this, design information was extracted from the Fortran source code and entered into a software development environment. The extracted design information was used to implement a new version of the program written in Ada. This experiment revealed issues about recovering design information, such as, separating design details from implementation details, dealing with incomplete or erroneous information, traceability of information between implementation and recovered design, and re-engineering. The reverse engineering process used to recover the design, and the experience gained during the study are reported.