Tourism 4.0 integrates Industry 4.0 technologies into tourism services to enhance visitor experiences and improve destination management. This study presents the design, implementation, and pilot validation of an integrated IoT–Augmented Reality (IoT–AR) cyber-physical urban node developed for smart tourism infrastructure in Baños de Agua Santa, Ecuador. The system combines distributed environmental sensing, LoRa-based communication, edge-level preprocessing, cloud data management via RESTful services, and immersive visualization through a cross-platform augmented reality mobile interface. The development followed the TDDM4IoTS methodology, adapted into five phases covering requirements analysis, technological design, modeling, validation, and deployment. The architecture supports contextual real-time information delivery while maintaining low power consumption and robustness under heterogeneous connectivity conditions. Field tests confirmed stable communication between sensor nodes and the gateway, as well as reliable AR marker recognition under varying light and distance conditions. Usability evaluation using the System Usability Scale (SUS) yielded a mean score of 84.38, classified as excellent, with high internal consistency (α ≈ 0.89). The results demonstrate technical feasibility and strong user acceptance, providing a scalable and replicable model for interactive IoT–AR urban systems in smart tourism environments.