Aste Nagusia / Semana Grande Activity · Donostia/San Sebastián, Donostialdea, Gipuzkoa Image of Donostia/San Sebastián, not of the place itself. The city's main festivities, held every year during the week that includes August 15. semana del 15 de agosto Photo: Gotzon Egia (CC BY-SA 4.0) What to see and do in Donostia/San Sebastián