On arrival in Madrid, check in. If you have the time and inclination to hit the streets later in the day, I recommend finding the nearest 100 Montaditos (a Spanish tapas place, of which they really have 100 to choose from). Try some of them, even the more notable ones (like the baguette with kinder bueno) will surprise you. If you have extra time, take advantage of the recommended programme below, but you can also catch it on other days. 

Today you will visit the Real Madrid football stadium, then explore the other sights of the city and visit one of the meze of your choice. 

Today you will visit the largest park in Madrid, where you can take a cable car to the top of the hill for a beautiful view of the whole city. Afterwards, you will walk through the beautiful neighbourhoods and visit the Museum of Illusions.