San Sebastián (sän sābästyän´), Basque Donostia, city (1990 pop. 183,944), capital of Guipúzcoa prov., N Spain, on the Bay of Biscay at the mouth of the Urumea River, in the Basque Country near the French frontier. Picturesquely situated at the foot of Mt. Urgull between the river and the Bahía de la Concha, it has attractive beaches along the coast. With the completion of the railroad from Madrid in 1864, it became the summer residence of the Spanish court. It remains one of Spain's most fashionable seaside resorts and is the site of several annual international jazz and film festivals. There are fishing, metallurgy, cement, food, and machinery industries. The city was rebuilt in the 19th cent. after its virtual destruction in the Peninsular War, when it was the scene of a bloody battle between Wellington and the French (1813). The San Sebastián pact, or republican manifesto, which precipitated the fall of the Spanish monarchy, was signed there in 1930.