The flag originates from the insurgency movement against the colonial authorities which began on July 20, 1810, during which the rebels wore armbands with yellow and red bands, as these colours were those of the Spanish flag used as the flag for the New Kingdom of Granada.

In October 9, 1952, exactly 142 years after these events, decree 555 of 1952 officially adopted the patriotic armband as the flag of Bogota. The flag of Cundinamarca follows the same pattern, plus a light blue tile which represents the Virgin Mary's cape.

The flag itself is a yellow band above a red one. The yellow denotes the gold from the earth, as well as the virtues of justice, clemency, benevolence, the so-called "mundane qualities" , long life, eternity, power and constancy. The red denotes the virtue of charity, as well as the qualities of bravery, nobility, values, audacity, victory, honour and furor, Colombians call it the blood of their people.


http://www.mundoandino.com/Colombia/Bogota