Longest ancient Egyptian festival

One of the most notable celebrations in the ancient Egyptian calendar was the annual Festival of Opet, which took place during the second month (usually October–November) of Akhet (the season of flood or inundation). When established in the 18th Dynasty during the co-rule reign of Hatshepsut and Thutmose III (1473–1458 BCE), the festival tended to play out over 11 days. By the time of Ramesses III, circa 1187 BCE, it had increased to 24 days, and after his death in 1156 BCE, there are records of it lasting 27 days.

The Festival of Opet focused on the themes of fertility and rebirth, and sought to cement the divine connection between the reigning pharaoh and the gods with a series of processions and rites centred around the temple sites of Thebes (now Luxor) on the eastern bank of the River Nile. It was believed that the reconnection between the king of the gods, Amun, and his mortal incarnation would assure a plentiful harvest in the year ahead, once the life-bringing floodwaters had receded.