In the Puerta del Sol, a plaza of Madrid, since 1950 the center of the Spanish national road network, dubbed Kilometer Zero, can be found.

The oldest building on the Puerta del Sol is the Casa de Correos (old Post Office).  The building has the famous clock whose bells at midnight on December 31st mark the time for the traditional 12 grapes that the large majority of Spaniards eat to celebrate the end of the year.