By public transport:
Take Metro B to the Rebibbia stop. Exit the metro and walk (50m) to the bus stop for the GRA (you have to cross the street). Take a bus (41, 40) which takes you to the "Casale Cavallari" stop. Get off and walk to street number 1166 in Via Tiburtina which is about 100m in the direction of GRA.  from the bus stop.
For better orientation (once you get off the bus): you will come across a Mc Donalad's, which you have to pass, and you get to the sliding gate of the area (fenced) where the Pianeta Elettronica office is located. From the gate you can see immediately the headquarters of Honda and Opel. Enter the gate and take the small road that is located on the front between the Honda and Opel buildings.
At the end of this road (about 50m) the blue entrance visible in the photo below will be visible.

By car from the GRA:
Take the Tiburtina exit of the GRA (SR5)  in the direction of central Rome. The Pianeta Elettronica headquarters is located about 300m from the GRA exit in Rome on the opposite side of the road to your direction of travel, once you exit the ring road (therefore accessible by taking Via Tiburtina in the direction outside Rome). Therefore it is necessary to take Via Tiburtina, towards the center, and make a U-turn as soon as possible.
At this point, proceed straight until you reach number 1166 in Via Tiburtina. You will arrive in front of the entrance (sliding gate). Since it is not possible to park on Via Tiburtina, it is advisable to turn into one of the crossroads of Via Tiburtina to enter Via Casale Cavallari (the road that goes behind the building where the office is located).    

By car from via Tiburtina:
Take Via Tiburtina until you reach number 1166. Since it is not possible to park on Via Tiburtina, it is advisable to turn into one of the crossroads of Via Tiburtina to enter Via Casale Cavallari (the road that goes behind the building where the office is located ).