The study presents the objectives, methodologies and technical features of a monitoring system designed in the context of a national research project proposing innovative technical solutions for smart dairy farming in order to increase the herd productivity. The main objective of the project was to improve environment conditions and animal welfare of dairy cows and consequently enhance reproduction and production. To this regard, the system described here has a fundamental role operating as a tool for a more efficient management of the herd and of the herd housing. In fact, in the last years, animal control techniques and farm environmental monitoring have been developed, with increasing intensity, through the integration of Information Communication Technology (ICT) systems and models for the analysis and interpretation of the data collected. In this field, the Smart Monitoring System (SMS) described here could be effectively implemented in order to increase the animal welfare but at the same time increase the animal production. The integration of different type of sensors, different type of data and different type of models is at the base of the modern techniques for herd management and of the tools aiming to increase the dairy sector sustainability. The system integrates specifically designed sensor networks in a customized system architecture. It allows the acquisition of big data time series about physical and environmental conditions of the facilities hosting the cow herds starting from the collection of both indoor and outdoor environmental features, enabling a smart control of the facility, a diagnosis of the operating conditions, and early alerts in case of anomalies. The system has been developed to work in several environmental situations and is able to make the data remotely available in real time in a cloud.