The correct answer to this open question is the following.
My detailed itinerary for visiting the top four cities for exploring the history of this would be this one.
Country: Spain.
Monday, August 10. Welcome to Madrid, the capital city of Spain. Hotel check-in and dinner at the hotel restaurant.
Tuesday 11. Downtown Madrid. Visit their typical colonial streets and neighborhoods (three hours). Lunch at "Ole Pinchos."
13:00 Visit to the world-known "Del Prado Museum," to admire their classic painting collections. Dinner at "Chorizo and Queso" restaurant. End of the day.
Wednesday 12. Early morning departure to Barcelona, a beautiful modern city and its beaches. Noon. Arrival at Goudi's "Sacred Family Church." An impressive building full of stories. 16:00. Dinner at "Fabada" restaurant. 17:30 walk through its typical squares and streets. 21:30 Check-in at the downtown Junior lodging house.
Thursday 13. Early morning departure to Toledo, to visit its medieval downtown, surrounded by its historic walls that protected from invaders. 17:00. Dinner at "Morcilla" restaurant and "Flamenco Party" at a local night club. We sleep at a close friend's home.
Friday 14. Early morning departure to Sevilla, to enjoy the artistic neighborhood and to attend a philharmonic orchestra concert at the world-famous theater "La Maestranza." We sleep at the student's dorm in the local College of Arts.
Saturday 15. Return to Madrid after breakfast.