Donostia/San Sebastian is located in the northeast of the Spanish Basque Country: 110 km from Bilbao, 500 km from Madrid, and 800 km from Paris. This charming medium-size city is set in a pintoresque countryside, on the edge of the Biscay Gulf and surrounded by mountains. You can get a map with higher resolution here
Useful external links about the city and the Basque Country are, respectively:
http://www.sansebastianturismo.com (Spanish, English, French)
http://www.euskadi.net (Spanish, English, French)