Many of the great wineries of the La Rioja region welcome visitors. (Note: Some require advance reservations, often via their websites, for tours and tastings.) Here are three of my favorites:
Compañía Vinícola del Norte del España
This well-respected wine producer has four different wineries: Imperial, Viña Real, CVNE and Contino. All of them receive visitors, but the striking underground modern winery by French architect Philippe Mazières at Viña Real is particularly worth visiting. The estate offers catered picnics at a modern pavilion in its vineyards afterward.