Parking for stop to see the historical district

Hi, We will land at OPO at 10 AM and drive to the Douro Valley. We would like to stop and have a look around Amarante's historical district and possibly have lunch. Does anyone have parking advice to give? Afterwards we'll drive onto Lamego and stop at a few places before stopping at our B&B in Ervedosa do Douro. All advice much appreciated! Sharon