"Now this is a game changer," I proclaimed the first time I tried port wine.

My viticulture instructor just laughed, knowing that I - like the rest of the class - was naive, newly 21 and looking to get drunk with terrifying efficiency.

As he described the merits and history of port, everyone perked up at the mention of its higher alcohol content (20%, thanks to the added brandy) and sweeter taste relative to normal red wines. It was delicious - dangerously smooth but also saccharine enough to make it difficult to down more than one glass at a time.

When I arrived at my hostel in Porto, the first thing I did was book an all-day wine tour for the following day. I'm generally not the biggest advocate for guided tours, but as we drove through the narrow, winding roads that criss-crossed the steep, terraced hills bordering the wine-producing Douro Valley, I was glad I had signed up. I wouldn't fancy making the drive by myself, let alone after a few drinks. Not to mention that during the ride our guide, a wry late twenty-something local, gave us her insight on current events ranging from the protests in Brazil to the current economic state and how it affects her generation.

The first stop was Caves da Reposeira, producer of sparkling wines similar to champagne. We only tried the dry variety so nothing particularly stood out about the place. Next was Quinta do Tedo, a small operation (they still crush the grapes by foot) owned by a French family that recently turned organic, that produces table wines, olive oil and, of course, port wines in all varieties (pink, tawny, ruby, vintage). Nestled in the hills just between the Douro River and the 41-acre lot that yields all their grapes and olives, it was a dream. (Also they let us sample each type of wine and port; most wineries tend to be stingy with the tastings). I loved the rosé port wine, but unfortunately they don't currently ship to the US.

Following a brief lunch break, we made our last stop at Aveleda. Technically located outside the valley, closer to Porto, this family-owned winry also serves as part museum and part farm, dating back to the 18th century. We finished our tour of the grounds - a welcome change from musty old cellars - with wine and cheese overlooking the vineyard. A place that only does whites and rosés? That's my kind of winery.