Travel To Castlerotto from the south. I would advise taking the train to Bolzano and then a bus to Castlerotto directly. Why? First it is inexpensive, about 3E per person. But more impt, quicker and less complicated. We went to Castlerotto by taking the train to Ponte Gardena Laion. But there is no train staff or window, no taxis; the staff at the train station cafe called, and after several tries did get a van to take us. We were charged 30E. The only downside for taking the bus to or from Castlerotto rather than the train and taxi via Gardena is that the road for the bus is curvy and a little scarey.
Oh, and one other thing about Castlerotto, they have different markets in the main square almost every day. Wednesday is for local crafts. Among the booths, the weaver is remarkable with beautiful bags and scarfs that would cost far more in the states. We paid 35E to 40E for several scarfs, and regretted we had no need for the carry bags, handbags and other things.