Most recommended city

Three days is a short visit, so I'd want to choose a place from which I could get to the study location easily, not wasting one of my days with connecting airline flights or a flight followed by a long train ride. It would help a lot to know where your student will be studying. The dates of your 3-day break could also matter. Finally, your origin airport will determine which European cities are easiest to reach.

Skyscanner.com is the website I use to explore intra-European flights.

Thank you - I guess I should have said the 3 days do not include our travel days. It will be towards the end of June - I didn't want to stay close to the city of study since the class will be visiting local areas. I want to be somewhere my student won't get to visit. I will check out Sky Scanner, thanks!

I would pick a city in Spain that is not where the student will be--maximizes time and money.
Portugal could be a good option, or Ireland, as Aer Lingus and TAP Air Portugal appear to have many sale fares in addition to being shorter flights.

Our suggestions would be more beneficial if we knew a bit about your families interests. But I would say use Acravens advice and look at Skyscanner to find the quickest flights to that city. I have not looked at logistics and only guess at your interests, but…..

Amsterdam
Munich
Lisbon
Venice

Spain is a big place. How about telling us where in Spain? Does he/she/it/them /they--I dont want to offend anyone--know what field trips the college will take them on?

I prefer using Google Flights to search for flights as it shows your choices more concentrated and with less ads.

You don't say where your student will be in Spain, but Barcelona and Madrid are very important travel cities. We also loved visiting Granada.

We were amazed how inexpensive it was to travel in Spain in comparison with France and England.

Krakow or Salzburg, are lovely destinations for a short trip and will be very different from Spain.

See if you can get an inexpensive flight from Spain to Venice. If so, then that would be my suggestion. It is one of the most unique places we've ever been. The only downside (if one can call it that) is that it will make you want to return and spend even more time there later.

Thank you, everyone, for the replies. I am trying to protect my student's privacy so didn't want to provide details. I do appreciate all of the suggestions!

TC, thank you - I have been leaning towards Venice

privacy is fine, and worthy.

With all the millions of people in Spain, and however many traveling in and out in the next 4 months, it is unlikely that naming a convenient airport could do very much to identify you or them. Yet you might get a better answer to your question. Hasn't mentioning Venice already blown that cover as much as the city or region of Spain? Just trying to help

I'd go with Prague or Berlin.

Check where Easy Jet or a similar airline fly from their Spanish city and go with the one you most likely would not return to visit the whole country. That will give you something unique to remember.

My suggestion is for Lisbon, which is a walkable city but also has good public transportation system.

I'll put in another vote for Venice..