Mosaic Hostel is located within a 5 minutes walk from Termini train station.

Exit Termini Station at Track 22(with the train tracks at your back, track 1 is on the left hand side of the station).

Make a left on Via Giolitti, and then take your second right down Via Cattaneo.

Continue down Via Catttaneo, until you reach #23 (will be on the left hand side of the street). Ring the bell to enter.
Mosaic Hostel is on the 1st floor (above ground floor)

From Leonardo Da Vinci Airport (Fiumincino - FCO):
Follow the signs for 'ai treni.' At the platform, buy a ticket for the non-stop train to Termini (11 Euros).
You can buy tickets from either the ticket window, the vending machines, or the tabacco store near the tracks. Then follow the directions "From Termini Station".

From Ciampino Airport (CIA):
Take the Terravision bus shuttle for 8 Euros. The bus will stop on Via Marsala. Walk down Via Marsala to the Termini station side entrance & follow the directions "From Termini Station".
NB: Please please careful of pickpockets; they have begun to target the area that the shuttle arrives/departs from.
By another way the blue Cotral Bus service connects Ciampino Airport to the Anagnina Metro A (underground) station. Tickets can be purchased at the vending machines located at the bus stop or inside the airport. Once you arrive at Anagnina, buy a metro ticket and get off at Termini (about the 15th stop). Follow the directions"From Termini Station".