Plaza Mayor, another major tourist destination. It was built in the early 1600's. The first public ceremony held here was the beatification of St. isadore the Farm Worker. The coolest thing about St. Isadore is not that he is the patron saint of Madrid (St. Farmer/ patron saint of Madrid, makes sense only in Spain) but rather that he was married to Saint Mary Of The Head. She has that sobriquet because her head was preserved and paraded around to bring rain.
