Colchagua valley in central Chile hosts rich soils watered by the Tinguiririca River, allowing the production of some of the finest wines in the world. In fact, Carmenère, a Bordeaux grape thought to be extinct for many years was actually rediscovered in Chile in the 1990s and now produces some of Chile's most celebrated wines.
Tours are available to follow the Colchagua Wine Route - covering a total of 14 vineyards. Ruta del Vino has full day tours including transport starting at £37. Included in such tours, there is often a showing of the wine cellar of the vineyard and several wine tastings.
For alternative ways of seeing Chile's wineries, Santiago's most popular tours are run by La Bicicleta Verde and start at £22. Their bike and wine tour will take you 40 minutes south of Santiago (their driver will pick you up from your hotel) to Maipo Wine Valley where you will collect your bicycle. The tour includes several vineyard visits, wine tastings and a traditional Chilean dinner (and of course more wine) in a local restaurant in Viña Santa Rita.
This is a great way to see the vineyards, but there is quite a bit of biking involved (a full day tour lasts 7 hours), so if you prefer to take it easy, you may be better opting for a tour with bus transport included such as the Ruta del Vino trip mentioned above.