Italy - Best way from Rome to Castel Gandolfo

Hello,

What is the best way to get from Rome to Castel Gandolfo? I will be staying for one night and returning to Rome. I will not be renting a car.
Thanks for any help you can provide.

First off it's Gandolfo with an A. I think you have two public transportation options.
There are relatively frequent trains (looking at the TrenItalia schedule it looks like almost hourly weekdays, every two hours weekends) from Termini to Castel Gandolfo on the Termini-Albano Laziale regional train line. The trip is about 45 mins.
Option 2 is taking the Metro A to Anagnina and switching to a Co.Tra.L. bus. On their web site they have PDFs of bus schedules (not sure how much these can be trusted) from Anagnina (http://www.cotralspa.it/PDF_Orari_Comune/_Anagnina_%5BMetro_A%5D.pdf) and from Castel Gandolfo (http://www.cotralspa.it/PDF_Orari_Comune/Castel_Gandolfo.pdf). Please note the different times for 'feriale' (weekday) and 'festivo' (weekend/holiday) as well as the Saturday exceptions (NS and SAB).
I would take the train as I have an inherent mistrust of buses. Good luck!

Thanks for the info!

There is indeed a Castel Gandolfo just outside of Rome, near Lake Albano, that is the summer residence of the pope.