Once, when you feel the sweetness of the Spanish paradise and the infinite beach stripes, the second time when the passion passes mercilessly through each of your veins to reach your ultimate goal – the heart, the third time when you try paella and you don't want to bite the last piece, the  fourth time, when without permission your body dragged a foot in the vortex of Paso Doble, the fifth time when the Raging Bull tries to lowering you on its horns and improve his record of accurate hits during the chase of the festival "San Fermin", the sixth time when the Sun caresses your face and ardently explains that there is almost no day off in the Sierra Nevada, and the seventh time when the spiritual aspiration prevails and you try to rediscover yourself, walking the Divine route camino. Well, I guess these are the first seven deadly sins you have to make in Spain. Consider them the first dance step of a passionate dance that can last as long as your body allows.
Surely visit the centre of Madrid. Before you start your first walk in this enchanting town and drink the elixir of the beauty of the dream named Spain, turn the TV out of curiosity. "Los productos necesarios son 1/2 kilo de tomate maduro, 1/2 pimiento Verde..." (the necessary products are 1/2 pounds ripe tomatoes, 1/2 green pepper..). These 10 seconds are enough to speed up your exit. 
You have exactly three days to experience the endurance of your senses in the fourth-largest country in Europe. Every tourist should know that touching Spain can be burned by hot landscapes and wonder where reality begins, falling from a great in an even greater era. If you carry binoculars with you and look at the Northeast frontier, your eyes will crawl the top of the Eiffel Tower, to the south you will end up in Marrakech and imagine that you  own the Moroccan palace El Badi Palace, and in the West you will become a captive of Belém tower in Portug Aaliyah. 

In three words, Spain is a time machine. The first stop is the Royal palace in Madrid, where an ordinary servant can feel like a king. This imposing dimensional, architecture and encompassment of the epoch building is used by the royal family, but not often.  Tourists have the opportunity to peek in over 50 of the luxurious rooms and to enjoy  where one of their fellow admirers does not exclaim: "Cierra Tu boca! Es Indecente "(Close your mouth. It's not right to stare like that!). 
Ah, Madrid... Days will not be enough for you to take in the greatness of Plaza Mayor Square and the strict view of King Philip III, who draws attention to each one who dared to face him. If you value art, dress in propriety and forget the Spanish passions for a moment and grasp the brush and outline the contours of the magnificent paintings of Kordučo and the frescoes of Velázquez in the "Enkarnasion" monastery. If your creativity has inspired you, you can visit the Prado Museum with hundreds of unique creations in the town fund and over 2 million tourists a year. 
Ladies and gentlemen, next stop, Barcelona. Prepare your pen and paper because time stops and the wonders of the city are more than you think – the church Cathedral "Sagrada Familia" and a whole "Gothic quarter" are at your disposal. There you will meet the architect Antonio Gaudi, who created almost everything that fills your eyes right now.