Spain is an enchanted destination for all types of travelers.

There are castles from the Middle Ages, celebrated works of contemporary architecture, rustic tapas, and Michelin-rated restaurants. There is world-class surfing, skiing in the Sierra Nevada, cycling for all skill levels, and a wealth of cultural activities that are unique to the Iberian Peninsula. And, of course, there is the wine.

Hemingway was on to something with his love of this country.

Portugal is equally captivating: Fado singers, ornate Manueline architecture, colorful Azulejo tile work, rugged beaches and seafood riches. Combine all these with a staggering list of indigenous grapes and diverse wines, and you get a culture that is distinctively and romantically Portuguese.  

An efficient rail system crisscrosses through Spain and connects its major cities. Travel is made easy if you prefer the well-beaten path. Knowing that, it's usually the toughest journeys that are the most rewarding.

Navigating the 350-mile-long river basin of the Duero River, as it meanders west through northern Spain and into Portugal, does require a car, a good map and some fortitude, but it's well worth the effort. You didn't think we were going to let you take the nice, comfy train, did you?

Starting in Madrid, it's about a two hour trek north to the town of Penafiel, which is known for its 10th century castle and a medieval square that still hosts bullfights. Penafiel is also at the center of the Ribera del Duero D.O. (Denominacion de Origen). This wine region is blessed by a large share of superstar producers. Estates like Pingus, Vega Sicilia, Pesquera, Emilio Moro and Abadia Retuerta are all within a short drive of Penafiel. Ribera del Duero is essentially red wine country. Most of the wines are made from 100 percent Tinto Fino (Tempranillo), although Garnacha (Grenache) and small amounts of international varieties are also used in blending.

Leave Penafiel and head west for an hour along the river. You'll pass the town of Valladolid. It deserves a visit. The Plaza Mayor, one of Spain's first great plazas, is centrally located within Valladolid. It is a large rectangular space, bordered by the Casa Consistorial (Town Hall), the 19th century Zorilla Theater, and a succession of granite arcades. The Plaza Mayor has a breathtaking simplicity that encourages spontaneous conversation, so strike one up with a local and find out the best place to enjoy authentic tapas and local wine.

Within a stone's throw of Valladolid is the white wine region of Rueda. Verdejo is the main grape used here, and the crisp, dry wines are often clarified with local clay. Most Rueda whites are aged in stainless steel to retain purity and freshness. Additionally, there are some examples aged in oak or blended with Sauvignon Blanc and Viura. Bodegas Naia is consistent with tank-aged Rueda. Try Belondrade y Lurton if you are curious about oaky styles. Small amounts of sparkling wine, rosé and red wine are also made in the Rueda D.O.