I will be visiting Rome later this year and hope to spend a day visiting Albano (where I once lived many years ago). I would also like to visit Castel Gandolfo on that same day trip from Rome. Is it possible to purchase a round-trip ticket from Termini, Rome to Albano Laziale and then just get off at Castel Gandolfo and (a few hours later) and then simply get back on the train with the existing round-trip ticket to complete the outward leg to Albano? Or do I need to purchase another one-way ticket to get from Castel Gandolfo to Albano (a distance of only about 2 km).
Of course, I know I have the option of just walking from Castel Gandolfo to Albano and maybe that's the right thing to plan on since it is so very close - but I hear that there is a lot of car traffic on the local roads these days and I remember those roads have little space on the side for walkers. So perhaps it is now an unpleasant and dangerous walk. And then there is, of course, always the possibility of bad weather that would make a walk unpleasant.