Answers:

rhia
Halifax

Granada is upwards of eight hours by train from Madrid, so that may not fit in with your plans.

Zarragoza, which is halfway between Madrid and Barcelona, is pretty fantastic!

sipes23
Crystal Lake

And four by bus, or maybe it was a bit longer, but far.

courtneyRM
Buffalo

This is the Basilica in Zaragoza.

Zaragoza is absoutely gorgeous. Check out the restaurants, some of them are pretty interesting.
And make sure to go to the Plaza Mayor when you’re in Madrid! GO.