This plaza is at least 500 years old, if not older, and contains three historic buildings from three different periods. Face the plaza with your back to Calle Mayor to take it in:
To your left is the late medieval (15th century) Casa y Torre de los Lujanes, the oldest house in Madrid. The tower is the oldest part, constructed in the early part of the 15th century.
The house attached to it was built in the later 15th century. It was in the Lujanes family home and hence the name given this surviving medieval home.
If you look at the side wall of the tower, within the small passageway, you enjoy the oldest doorway in Madrid, a beautiful Islamic horseshoe archway that contains some of the original flint used in building Muslim Madrid. You can make it out as it is the darker colored stone. Today this arch is the gateway to the offices of the Sociedad Economica.
In front of you, to the right of the Lujanes tower and house is the Casa de Cisneros, built for the Cardinal Cisneros in 1537.
On your right is the Casa de la Villa, Town Hall, designed in 1640 by the same Hapsburg architect of the Plaza Mayor, Juan Gómez de Mora (along with several other architects). The city moved its government to the elaborate and far more spacious Palacio de Communicaciones, the main post office’s building on Plaza de la Cibeles in 2007. This older city hall is still in use.