San Juan de Duero, also known as Arcos de San Juan de Duero, forms a group of Castilian Romanesque architecture located on the outskirts of the city of Soria.

What can be seen today, the church and the cloister, are nothing but the remains of a monastery of the military Order of the Hospitallers of San Juan de Jerusalem or San Juanistas knights, built in the first half of the 12th century on the banks of the Douro River and which remained inhabited until the 18th century.

The church is very simple, with a single nave with a presbytery and apse; the former, with a pointed half-barrel vault, and the latter, semicircular with an oven vault.

It would not have anything striking if it were not for the two temples arranged, one on each side of the presbytery as an iconostasis, so that the space that remained between them could be closed and the priest hidden at the time of consecration, following the norms of the Greek rite. It consists of two canopies, one with a spherical dome, and the other conical, but in both cases spiked and mounted on columns with a quadruple shaft and unique capital and base.

The capitals have figurative reliefs of meritorious work staging evangelical and allegorical passages. In one of them the Virgin is contemplated lying in her bed while a woman arranges the pillow. Saint Joseph appears very deteriorated, the child in the cradle and, above all the scene, the mule and the ox under a star. It is curious to see how there is such an abundance of images, that the sheep of the Annunciation invade the scene of the Adoration of the Kings and the Virgin and Child whom they adore are so angled that they appear crooked.