For software architects involved in maintaining existing software systems, understanding the architecture is a crucial task. They have to comprehend the evolution of a system and the rationale behind design decisions to avoid architecture erosion. This is challenging due to frequently outdated documentation and incomplete knowledge about the system, which especially applies to long-living systems. Therefore, it is necessary to retrieve the missing information straight from the existing system. Most existing approaches are limited to reconstruct the structure of a software system by preferably analyzing static dependencies between components, without considering their behavior. However, the usage of technologies determines the behavior of a software system. In this paper, we propose an approach to identify technology features in existing systems. Used technology features are fundamental facts which support architects to understand the software architecture and to find alternative technology solutions. We provide tool support and present first results of the identification of technology features in open source systems.