About 8km southeast of Berlanga de Duero stands the Ermita de San Baudelio, the simple exterior of which conceals a remarkable 11th-century Mozarabic interior. A great pillar in the centre of the only nave opens up at the top like a palm tree to create delicate horseshoe arches. It's one of rural Castilla's most surprising finds.
Check with the tourist office in Berlanga to make sure the opening hours haven't changed.