Spanish architect. He was active in both Valladolid and Seville during the same period. In the capacity of Master of the Works (1527), he collaborated with Juan de Alava (c. 1480-1537), Francisco de Colonia (c. 1470-1542) and Juan Gil de Hontañón the Younger (active 1521-1531) and his brother Rodrigo Gil de Hontañón on the third Colegiata of Valladolid, modifying its design by setting the base of the towers on chapels with vaulted niches. A gigantic Gothic edifice, the Colegiata had a nave separated by piers from the aisles, which were lined on their other side with chapels containing vaulted niches; the building was absorbed into Valladolid Cathedral in 1580 by its architect, Juan de Herrera, although he kept to the outline of Riaño's scheme. From 1523 Riaño lived in Seville, where he designed and supervised the construction of the Ayuntamiento (City Hall, 1527). The elongated three-storey building has a richly decorated façade on the south-east side, articulated by pilasters on the ground floor, by attached and free-standing columns on the piano nobile and by round windows on the upper floor. This Renaissance envelope encloses a Gothic interior, its vaults interwoven with Renaissance decoration. As Master of the Works at Seville Cathedral (1528), Riaño designed the Sacristía de los Cálices in a completely Gothic style, as well as the Capillas de los Alabastros (1532), in which he exhibits a fully Plateresque sense of style, characterized by a great richness both in the carvings and in the materials employed. He built the main sacristy (1530) as a Greek cross inscribed in a square, articulated to the height of the cornice by Corinthian pilasters and half columns in a Greco-Roman style that reflects the influence of Diego de Siloé at Granada Cathedral. Above, the square is transformed into an octagon to support the dome. Both in structure and in decoration, Seville Cathedral is a striking example of the triumph of Renaissance architecture in Spain. //