The good: Beautiful apartment (exactly as pictured) in a great location and neighborhood. Good communication from the host (with a massive exception you will see below).
The BAD: The “air conditioning”…. It was 104 degrees outside when we checked in. When we got into the apartment it was >90 degrees inside with no moving air anywhere except the bedroom which has a ceiling fan (no other fans in the apartment). It was a friend of the host who checked us in and didn’t know anything about the AC so we messaged the host directly saying it was miserable in the apartment and the AC appeared to be broken. Rather than trying to help or looking into it we were told the AC worked fine since the previous renters did not complain (no proof other than that rude statement) and that the air conditioning is controlled by the building and comes through the floor. The floors were not cold in any way and it was so uncomfortable throughout the apartment that we left a few hours after checking in without even staying a single night.
Long story short: A great apartment with either no AC, or a system that cannot make the apartment comfortable during the Madrid hot summers. Do not recommend staying here when the weather is warm.