Festivities of invierno de Grisel Activity · Grisel, Tarazona y el Moncayo, Zaragoza Image of Grisel, not of the place itself. Grisel's winter festival is held beside a restored 15th-century castle, seat of the Amigos de los Castillos de Aragón association, in a district where the Pozo de los Aines sinkhole opens. Photo: Eloy Cotallo (Public domain) What to see and do in Grisel