• Brief description: Highpoint of Spanish Gothic architecture, construction on it began in 1226, during the reign of Fernando III el Santo (the Saint). In 1493, when the Catholic Monarchs were on the throne, the vaults of the interior central nave were closed. Both the exterior and interior are worth seeing, especially the two-story choir made of stone and wood, the main altar (in front of the choir), the paintings by "El Greco" in different parts of the church, and the Hispanic Mozarabic chapel, where mass is still celebrated in accordance with this rite. The best thing of all is the Transparente, a skylight for illuminating the cathedral adorned with paintings and sculptures. 
• Cost: 11€ with audioguide. Free for Spaniards Sunday afternoons. 
• Length of visit: 1 hour.
• Hours: Monday-Saturday: 10:00 to 18:30. Sundays and holidays: 14:00 to 18:30.
• How to get there: Ticket office through Puerta del Reloj, on Calle Chapinería. Entrance on Cardenal Cisneros.