Traveling from Italy to Switzerland

alexandria, your question is almost too broad and general to answer without knowing what places you want to see, and how long you plan to be there. Are you working with a guidebook?

Depends where in Italy to where to Switzerland.
From Rome or points south, it is quicker to fly to Zürich, Geneva or Basel (whichever is better for your final destination).
From Florence and Milan definitely train, Venice is borderline depending on where you are going.

There are 1838 stations in Switzerland, you can get anywhere you want by train (including some places with no road access). Even if you fly, you will need to do the last leg from the airport by rail.

There are three rail lines from Italy to Switzerland, all go from Milan, so you will end up going through Milano Centrale station.
1) Lötschberg-Simplon route. Through two rail tunnels of the same name. Best for western Switzerland: Geneva, Berner Oberland and Bern.
2) Gotthard route, via the new long Gotthard tunnel. Best for central Switzerland: Luzern etc.
3) Bernina Pass route. The joker in the pack. Via the Bernina Pass to St Moritz and Chur in eastern Switzerland. Longest and most indirect route to most places in Switzerland. It is the most scenic, as it goes OVER the Alps (Bernina Pass) instead of through a tunnel. Worth it if you have the time.

You can look up trains on the SBB (Swiss Railways) website: https://www.sbb.ch/en This lists Swiss and Italian trains.
The Trenitalia (Italian Railways) website ( https://www.trenitalia.com/en.html ) only lists Italian and cross-border trains, so is not helpful when you need to get a Swiss train for the last leg.

alexandria,

I agree with the first reply..... it's difficult (if not impossible) to answer this question without some further information. Where are you travelling from in Italy and where are you going to in Switzerland? Travel by train (especially high speed trains) is generally the best method.

Could you elaborate on your reference to "cities"? Have you determined which cities you'll be visiting yet? If not, I'd suggest you have a look at the Rick Steves Italy and Switzerland guidebooks. You should be able to find copies at your local Library.

Yes, I should have been more specific. Cities in Italy I plan to visit... Rome, Florence, Venice & either Cinque Terre or Amalfi Coast.

Switzerland I plan to go to: Lucerne, Interlaken & Zermatt for sure, possibly Geneva area.

Among the places listed, Zermatt is a good place to go onwards from Italy. To there it's a 6-7 hour train ride from Venice or the 5 Terre.
From Zermatt you then move on to Interlaken and 'uzern.

alexandria,

Thanks for the additional information. You could consider travelling in the order Venice > Florence > Rome > Cinque Terre as that's an easy and efficient route by train, and minimizes travel times. The trip from Rome to the Cinque Terre is easy if you use one of the direct trains from Roma Termini to La Spezia Centrale (about 4 hours or so). From the Cinque Terre, it's relatively easy to reach Switzerland (usually via Milan), although it's often a bit of a longer travel day.

Are you planning on staying in the Berner Oberland or just visiting Interlaken as a day trip? IMHO, I'd skip the Geneva area and spend more time in the Lauterbrunnen Valley. I find Geneva a bit "underwhelming", although I enjoyed Lausanne. How many places to include will depend on how much time you have available.

Have you had a look at the guidebooks yet?

Geneva is definitely NOT a Tourist Destination. Bypass Interlaken and just use it to change trains to get to the Lauterbrunnen Valley which sits in a valley surrounded by towering alps. Cinque Terre is one of those places that's horribly overrun by tourists thanks to RS and his love of the villages.