A good place in a good position, but look closely at the maps - you cannot walk straight to the Vatican. There is a hill and huge walls in the way. Better to take any of the buses going towards the right as you exit the apartment building. If you walk 50m to the right there is a bar and tabacconist (marked with a sign with a large letter T) which sells bus and metro tickets valid for a single journey, 24, 48 or 72 hours. For the Vatican get off at the third stop - just before the bus enters a tunnel. Carry on and the most useful bus, 918, takes you all the way to to Piazza Venezia