Georeferenced street corners map

I'm sorry but I don't know where to ask this question.

I have to develop a navigation program in my artificial intelligence course. To do it, I need a city map. Probably Barcelona.

I don't which is the format of a map used in navigation systems like Tom Tom or Google maps, but if I want to use graphs, the format could be georeferenced street corners.

Ok. My questions are:

1. Where could I find city streets data to calculate a route between two locations?


2. How do you could such kind of maps?

Please, it this is not the right place, tell me where I can ask this question.