Going through this forum has been so helpful in planning Spain trip, now have a specific question. Sometimes we need a light meal, something to eat in our hotel room or a park. In England, we would pick up sandwiches at Marks & Spencer. in Germany loved the bratwurst stands. In Ireland, we bought sandwiches in small grocery stores in both Limerick and Galway. Madrid is a huge city. We're staying at hotel on Claudio Coello, 139, not far from the National Library and National Archaeology Museum. Does anybody have any recommendations? Are there likely to be any small markets, fruit stands, etc., in the area? We'll also be going to the Prado and Royal Palace areas during the day.
Thank you! Inexpensive restaurant and tapas recommendations welcome, too. Sightseeing time is short and simple food works best .

That is an upscale area you chose to stay in (Salamanca) but there are markets there as people live there, in addition to the stores, etc.

For one place, there is a Carrefour Express small grocery store at 18, Calle Hermosilla (near c/Velasquez) a bit north of Serrano metro stop, which isn't too far from there. Of course there is the major dept store El Corte Ingles a couple blocks from there on c/de Serrano and if it's like other ones in Spain, it has a grocery store in it.
https://www.elcorteingles.es/centros...ercial-serrano

There is also the Mercado de la Paz small market there not too far
https://www.yelp.com/biz/mercado-de-la-paz-madrid

Your hotel is quite a way north from the National Librery in Castellana.
The excellent supermarket at El Corte Ingles on Serrano is a good option.
If you google your hotel, t he map will show restaurants and shopping nearby.

sorry, I meant to say you are located in Castellana, (north of Salamanca.)

If you take a look at Maribel's Guide to Madrid you should find information on where you can grab a bite when out and about (www.maribelsguides.com/mg_madrid.pdf)

There are also a number of Museos de Jamon sprinkled throughout Madrid where you can get a fine sandwich at a reasonable price.

Museos de Jamon? Really? Time to move into present day Madrid where one can find some of the finest cuisine Spain has to offer. All one has to do is look around. See Carlos Marbona's Salsa de chiles at ABC.es @salsadechiles