It was built by French architect Jacques Marquet (1760 - 1768) at the Puerta del Sol as the central headquarters of the Post Office, and was designed in the Baroque style of the period. The combination of materials, brick and stone with wrought iron on the balcony, and the sculptural details of Antonio Primo are emphasized throughout the structure.

 The clock turret dates back to the 19th century and was a gift from the clockmaker Losada.

Each year on December 31st, it is this clock which marks the end of the year for the citizens of Madrid, and thanks to television, for all of Spain as well.

Previously, it was the headquarters of the Department of the Interior. It is currently occupied by the Presidential Council of the Community of Madrid.