Tower of the clock on la Casa de Correos at Puerta del Sol Square at sunset. Madrid, Spain - Stockfoto

Puerta del Sol's clock sits on regional Madrid government building in Madrid, SpainSpain's most famous clock, Puerta del Sol's clock, was built in 1860 by London based Spanish watchmaker Jose Rodriguez Losada and donated to the city of Madrid. The clock was first inaugurated in 1866 at the Real Casa de Correos and it still contains 98 percent of its original pieces. Casa Losada's watchmakers check the clock's working condition weekly, and even more often in the days leading up to New Year's Eve. Spaniards will celebrate the New Year when the Puerta del Sol's clock strikes midnight.