Dev Diwali, or Festival of Lights of the Gods, is the largest annual festival in Varanasi, India's holiest city. On this date, according to my guide, all the Hindu Gods descend upon Varanasi to partake in the festival. On the eve of Dev Diwali, the river banks are lined up with thousands of Diyas (or earthen lamps), and everyone -- from the old to the young -- gather on the banks to light up fireworks.