ARG-US (meaning “Watchful Guardian”) Remote Area Modular Monitoring (RAMM) is a remote, “unattended” monitoring system with a two-layered architecture: a wired Ethernet base layer and a wireless sensor network (WSN) overlay. Each RAMM unit is equipped with a suite of sensors that can be customized for the application environment, and multiple communication modules. The wired network, which provides normal, baseline data collection and communication, also keeps the batteries in the RAMM units charged via power over Ethernet. The RAMM units, each with its unique sensory and communication provisions, form a WSN using the wireless transceivers in the RAMM units. In this paper, we focus on testing of two RAMM systems deployed in a radiological facility and an office building at Argonne National Laboratory. Together, these two RAMM systems provided a testbed operating environment for studying the behavior and performance of the WSN, including its formation and transmission of selected sensor data across the WSN.