Which building's clock is heard during Madrid's famous New Year's Eve grape-eating ritual?

The clock heard during Madrid's famous New Year's Eve grape-eating ritual is the clock of the Real Casa de Correos.

The Real Casa de Correos stands on Madrid's Puerta del Sol and is one of the square's most recognizable buildings. Its clock provides the twelve midnight chimes used for Spain's tradition of eating one grape per chime, a ritual known as las doce uvas de la suerte.

The building was designed by the French architect Jacques Marquet and constructed in the eighteenth century. It later became the headquarters of the Madrid regional government, and its clock gained national importance through annual television broadcasts.

The clock's preliminary signals are not the twelve main chimes. Celebrations include warning sounds before midnight, followed by the sequence that begins the grape ritual. This distinction matters because trying to eat the grapes during the earlier signals would put participants out of step with the traditional countdown.