Hey @CaterinaOS , Madrid is a nice city, I was there 4 months ago and it was great. My sister lives there and I wasn’t in the hotel or apartment, but I can recommend you places that I found. Please check this link and you will find them.
Instead of place to stay, I want to share with you nice places where you can find really good food 
The first place is Oven Mozzarella Bar, located close to the Estación del Arte subway station and the Madrid Atocha Railway Station. Great choice for a dinner or lunch, amazing food and the staff there made us feel very welcome.
Another good option is Garden of Salvador Bachiller. The restaurant is hidden inside a department store and to get to the it, we had to ride the elevator to the top floor, where we arrived directly to a secret garden. The menu was varied and everything we tried was delicious.
The last one is La Berenjena, quite small but offered different food choices—from French to Asian cuisine. We found it thanks to the Explore tab on Google Maps. We had a great experience there.
During my stay, I took a short trip to one of the most beautiful cities I’ve ever been to—Segovia. Located an hour drive to the north of Madrid, Segovia is very easy to get to. We went by car and spent just a day there, but there’s a number of other transportation options, including trains, buses, and group tours. More adventurous visitors can even try the hot-air balloon ride to Segovia from Madrid.
If you get the chance to visit this city and only have one day, here in this post are my top three places and things to enjoy there.
I hope that these information will help you and have a great experience in Madrid. Please don’t forget to share with us afterwards.