We present a fully active-controlled He–Ne ring laser gyroscope operating in square cavity having a side length of 1.35 m. The apparatus is designed to provide a very low mechanical and thermal drift of the ring cavity geome- try and is conceived to be operative in two different orienta- tions of the laser plane, in order to detect rotations around the vertical or the horizontal direction. Since June 2010, the system is active inside the Virgo interferometer central area with the aim of performing high-sensitivity measure- ments of environmental rotational noise. So far, continuous unattended operation of the gyroscope has been longer than 30 days. The main characteristics of the laser, the active remote-controlled stabilization systems and the data acqui- sition techniques are presented. An offline data processing, supported by a simple model of the sensor, is shown to im- prove the effective long-term stability. A rotational sensitivity at the level of 10−8 rad/√Hz below 1 Hz, very close to the required specification for the improvement of the Virgo suspension control system, is demonstrated for the configuration where the laser plane is horizontal.