This article summarizes the experience of the development of a large commercial software system at ULTER Systems Ltd. as an example of the use of Eiffel as the development language and the Eiffel compiler by SiG Computer GmbH. It explains why Eiffel was chosen as the main programming language for the project. It describes the Eiffel compiler by SiG Computer GmbH and our experience in its use for large-scale projects.