want to travel from munich to rome by night train. where can I make an advance booking for a couchette? this could take place in Salzburg if required.
www.bahn.com
The NJ 295 departs from Munich Ost station.
Suggest to book directly at provider NightJet.
If you're making a reservation to go with a rail pass, then either a train station in Salzburg or elsewhere, or else by phone to OEBB are currently the best sources.