River of gold

With a title like that its no surprise this was a work trip - however I was actually assessing a tungsten deposit! Instead the gold around the River Douro is liquid gold because the region challenges my "home" (the Alentejo) to produce Portugal's best wine. While I must be diplomatic its fair to say the Douro produces wines which match the Australian way of drinking - i.e. wines to be drunk on special occasions or with specific foods, bottles to be put down for a few years - instead of the Alentejo which produces wines to be drunk every night of the year no matter what's for dinner (and to be honest they're both damn good so why pick one as better?!).
Because of the steep slopes the vines are planted on platforms cut into the side of the hills, often stabilised with brick walls, which gives the hills a tiger-striped appearance. Since theses platforms are the width of a vine and a person mechanical methods are pretty useless so technology hasn't helped the wine growers here much.
The real liquid gold is the "vinho fino" (fine wine) better known to us as port wine. Port "farms" like this one in Regua are all along the banks of the Douro. However don't let someone try to explain the difference to you between vintage port and aged port. Its complicated.