Festivities of Yésero Activity · Yésero, Alto Gállego, Huesca Image of Yésero, not of the place itself. Main feast of Yésero on the weekend closest to 8 September, for the Nativity of the Virgin. On 20 January a bonfire, the chera, is lit for San Sebastián, and on 5 August a pilgrimage is made to the hermitage of Nuestra Señora de las Nieves. Photo: Wikipedia / Wikimedia Commons (CC BY-SA) What to see and do in Yésero