One of the stars of Extremadura's Ribera del Guadiana wine-producing region, Palacio Quemado produces excellent reds and runs guided tours (including one by tractor), wine tasting and wine-tasting courses. It also has cellar-door sales. It's east off the A66 northeast of Zafra and you'll need to ring ahead to make an appointment and to ask for directions.
Palacio Quemado
Top choice in Extremadura