The objective is to design, implement, test and validate a dedicated Alert System (AS) for the monitoring of the public green, in particular those located inside areas of relevant historical and cultural sites. The proposed service monitors the health of vegetation by indirect estimation of bio-physical parameters using Sentinel-2; Landsat-8 and PRISMA satellite images, fused with high resolution satellite and/or UAV images. Additionally, the service monitors in real-time trees stability leveraging on a network of in situ sensors.