Visiting Spain for the first time

For our first time in Europe we decided to visit Spain. It was a long nine hour flight, but it was absolutely worth it. We first visited Madrid and the weather was perfect, we got to the apartment using the Metro, and it was really fast, once we got there the street was full of "classical" buildings that even though may be old-looking on the outside were modern and functional on the inside, we spent about 7 days there and then we went to Barcelona, the weather was way colder there but thankfully the apartment had a heating system and was pretty modern in everysense, we also used the metro and the Renfe to move around the city, both were really fast and intuitive so it was really easy to use without getting lost. We visited stadiums, museums and cultural centers in each city and even though Barcelona's official language is catalan, they also spoke Spanish so we had no problems.