September 16th, 1810 is the day that independence was declared in Mexico and over a decade later it was fully realized. Many in the United States mistakenly believe that May 5th or Cinco de Mayo and this date is celebrated in the U.S. as a day to enjoy all things Mexican, except perhaps the actual history of Mexico.
While like many countries, Mexico celebrates with parades, marching bands, the hanging of their national flag and having parties there is an interesting extra event that takes place.
Grito de Dolores("Cry of Dolores") or El Grito de la Independencia("Cry of Independence"), is re-enacted every year by the president of Mexico as well as other officials such as Mayors and Ambassadors from Mexico. This was the speech given that called the populace to come together to be free and spoken by Miguel Hidalgo y Costilla, a Roman Catholic priest. What the actual wording was has been lost but the tone and ideas have remained and are repeated at these events. The President of will typically do this speech the night before around 11:00 PM or at Midnight on a balcony at the presidential palace. He will ring a bell and recite these words.
(From wikipedia this is the translated wording)
Following the speech he will ring a bell. This same speech is given by the other official representatives of the country through out the world.
Links:
http://en.wikipedia.org/wiki/Grito_de_Dolores