Bright orange marigolds, glowing candles and faces painted like the elegant skeletons known as catrinas fill the streets of Mexico every year during the country's Day of the Dead celebrations.

Festivities begin in October and lead up to Nov. 1 and 2, when the souls of deceased loved ones are believed to temporarily return to earth to reunite with their families.

No one knows when the first observance took place, but it is rooted in agriculture-related beliefs from Mexico's pre-Hispanic era.