What Spanish city square hosts the famous New Year's Eve grape-eating countdown?

Madrid's Puerta del Sol hosts Spain's famous New Year's Eve grape-eating countdown.

At midnight, people try to eat one grape with each of the clock's twelve chimes. The twelve grapes are traditionally associated with the twelve months of the coming year, and finishing them is believed to bring good fortune.

The custom became strongly established in Spain during the early twentieth century. One widely cited explanation links its spread to a surplus grape harvest promoted by growers, although the practice also developed from earlier elite customs involving grapes at New Year.

Puerta del Sol is especially important because its clock is broadcast nationally. People across Spain often follow the chimes on television, while crowds gather in Madrid around the square's landmark clock. The grapes are eaten after the preliminary warning sounds, not during them.