A guide to the city can be found at IdealSpain.com. The Catedral de Santa Maria is one of themany sites to see. As for restaurants, Mario recommends Asador Sagartoki. This is a pintxo bar where traditional Basque dishes are presented as haute-cuisine.
Near Vitiora, is the village of Idiazabal. The village is known for its nutty-tasting cheese made from the milk of Latxa sheep.
Speaking the local language always helps to make friends. To say thank you in Basque: Eskerrik asko. For more phrases, try out this helpful site.