You can visit Casa details last Conchas, Old Roman Bridge and Aqueduct of Segovia in Salamanca.
Cute town filled with history and beautiful corners. You can walk the steps that Columbus walked when went to ask for financing by the Catholic Kings and enjoy its lively "Plaza Mayor", filled with people at any time of day or night.
Took a day trip from Madrid to Salamanca by bus with the local friends in Spain back in 2007.
A beautiful city two hours Madrid. A university town with lots of students everywhere and some cheap eats. Make sure to grab a seat at plaza mayor to people watch.