Peso da Régua, usually just called Régua, sits on the north bank of the Douro where the river broadens and the steep schist terraces of the upper valley begin to spread out. It is the natural base for first-time visitors: the train from Porto terminates here, river cruises start and finish here, and the N222 — the route everyone tells you to drive — runs east from the town.
Walk the riverfront, climb up to the Museu do Douro for context, and watch the rabelos (the flat-bottomed wine boats) come and go. Régua itself is not a beautiful town in the way that some of the higher villages are, but it is the right place to get your bearings before going deeper into the valley.