from Torino airport: there is a shuttle taking you to Torino downtown, next to Porta Nuova station, or you can take a taxi (the fare is usually 30-40€). Click here to check the airport transportation webpage
from Porta Susa train station: if you want to walk, click here for a map, or you can take tram 10
from Porta Nuova train station: if you want to walk, click here for a map, or you can take buses 33, 58, 58/
A link to GTT - Gruppo Torino Trasporti (Torino transportation system) can be found here.
---Hotel Bologna: hotel website, itinerary from Porta Nuova (recommended!), itinerary from Porta Susa. To get to Politecnico from Hotel Bologna you can either walk (map here) or take buses 33, 58, 58/.
---Hotel Diplomatic: hotel website, itinerary from Porta Nuova, itinerary from Porta Susa (recommended!). To get to Politecnico from Hotel Diplomatic you can either walk (map here) or take tram 10.
---Residenza Borsellino: website, itinerary from Porta Nuova, itinerary from Porta Susa. You can easily walk from Residenza Borsellino to Politecnico, here is a map (it's easier if you enter Politecnico from Corso Castelfidardo instead of Corso Duca degli Abruzzi).