Festivities of invierno de Oseja Activity · Oseja, Aranda, Zaragoza Image of Oseja, not of the place itself. Oseja's winter festival is held in honour of San Blas on 3 February, in a village whose castle was probably built between 1356 and 1369, during the War of the Two Pedros, and which in 1301 passed from the Order of the Holy Sepulchre to the lordship of the see of Tarazona. Photo: Viquipèdia (CC BY-SA 4.0) What to see and do in Oseja