The recent collaboration between the University of Genoa and the Archaeology, Fine Arts and Landscape Superintendency has led to the installation of a dynamic monitoring system on the Saint Lawrence Cathedral, one of the most ancient and important places of worship in Genoa whose construction began in the 12th century. Aiming to support the maintenance and preservation of the building, the monitoring system has been designed to assess the current structural health conditions of the church based on experimental vibration data. The network involves diverse sensing solutions: Force Balance accelerometers at low heights and MEMS accelerometers at the top continuously measuring the low-amplitude operational vibrations of the building as well as the potential seismic response to earthquakes, coupled with internal and external temperature probes to capture the local variations in environmental conditions. Measurements are acquired by independent acquisition nodes, synchronized via GNSS and sent to a central processing unit via cable or Wi-Fi for real-time processing—assessment of vibration level, dynamic identification, and modal tracking. The paper discusses the lessons learned from the design and installation of the monitoring system, and presents the first months of data collection and analysis, identifying the key challenges in achieving the continuous data-driven structural health monitoring of the church. The first findings of the research highlight a complex dynamic interaction between the church and the bell tower, which exhibit several close or fully coupled modes in the low-frequency band below 6 Hz, and how their natural frequencies are significantly affected by variations in ambient temperature.