transport europe public transport

Hello Eurotrip community,

You’ve been a great help to me while planning my trip, so I figured I would ask you a few more questions. I have a question about public transport within the cities, will it be expensive? We are going to spend roughly 26 days in Europe in the cities of: London, Paris, Amsterdam, Berlin, Munich, Florence, Rome, Naples, and Pompeii, so I was wondering should I worry about public transportation.