Foz do Douro

Foz do Douro sits where the Rio Douro empties into the Atlantic, and it marks the true beginning of coastal walking. The Jardim do Passeio Alegre, a shaded garden near the river mouth, makes a pleasant first stop. Beyond it, the Farol de Felgueiras lighthouse stands at the end of a long breakwater -- worth the walk out for views back toward the city, though it can be exposed in rough weather.

The Castelo do Queijo, a small 17th-century fort perched on a granite outcrop, guards the transition from river to ocean. The name -- Castle of Cheese -- comes from the rounded shape of the rock it sits on. From here north, the Atlantic is your constant companion.