The Time and Frequency Laboratory (here after indicated as TFL), realizes and makes available to the users the UTC(IT) time scale, the legal time scale for Italy. Generated by means of an active hydrogen maser (AHM) and supported by an ensemble of cesium beam frequency standards, hydrogen masers and cesium atomic fountains, UTC(IT) is synchronized via satellite (GPS and TWSTFT, Two Way Satellite Time and Frequency Transfer) with those generated by other international NMIs (National Metrological Institutes) and it is kept in agreement with the international time scale UTC (Universal Time Coordinated) computed by BIPM (Bureau International des Poids et Mesures). Also, TFL regularly contributes to the realization of the TAI (International Atomic Time) time scale, sending to BIPM the measurements results carried out following protocols defined at international level. The Laboratory is also devoted at disseminating the Italian legal time scale to the country through Radio/TV (RAI), Internet and phone, as well as granting for the traceability to UTC of oscillators hosted at Institutes and Industries. More in details, the TFL is housed in three areas, namely the MCR (Monitor and Control Room), the CCR (Cesium Clock Room) and the HMR (Hydrogen Maser Room). The CCR hosts six cesium clocks (Symmetricom – now Microsemi – High Performance HP5071A), while the HMR hosts four Active Hydrogen Masers (2 Symmetricom MHM-2010, 1 Kvarz CH1-75A and 1 T4Science iMaser3000) and the systems devoted to the generation of UTC(IT) time scale. The mentioned areas are provided with two air conditioning systems (main unit and the back-up one) maintaining the temperature at (23 ± 1) °C. The MCR, (23 ± 2) °C, hosts all the devices used for the TFL activities, like the synchronization and dissemination systems, as well as the monitoring and all the auxiliary ones.