I'm wondering how safe it is for a woman to travel alone on the Madrid Metro in the evenings. I will be staying in the northeast corner of the Salamanca Barrio, roughly a 20 minute Metro ride from the Centre. I have traveled on other subway systems in major cities but this is my first trip to Madrid.
It is safe you will not feel isolated, and you are staying the rich people area (not saying that you can't get mugged in Salamanca). The Spanish do things later than here in America meaning if you are out after 10 pm people are still at dinner or out in the streets. I was in Spain for 10 days a little over a month ago.
Madrid runs on a different time schedule than the US. You will find lots of people with you. Should be fine with the usual precautions.