The city is not too big to see on foot, especially the main attractions, which are fairly close to one another. For slightly longer journeys there are two taxi companies, and several bus routes - tickets are cheap, and you can buy them directly from the driver on board or for longer stays get a travelcard from one of the branches of the bank Caja Duero.
There is also a good bus service to Salamanca, Valladolid and Madrid among other destinations.