A leading data-center operator in the EMEA region, with multiple facilities spanning over 25,000 square meters, faced significant security challenges. The operator experienced interruptions in their internal IT network due to unsupervised work of third-party technicians. Despite having a high-end building control system that provided 24x7 monitoring and control to all the building’s infrastructure, the data center was vulnerable from a cyber perspective as it was connected to the IT network infrastructure. The operator launched an urgent OT cyber security project that included both IT-OT network segmentation and OT network asset mapping and anomaly detection. The main objectives were to harden the security of the server systems, secure the facility’s power supply and server cooling system, strengthen the segmentation between building and operational systems, create a visual OT network map, and set up a system for presenting supply-chain attacks that may threaten the data center through equipment vendors’ maintenance activities.