August 1st marks the Celtic holiday of Lughnasadh (pronounced loo-na-sa), which is the beginning of the grain harvest.
In days past, candidates for king would go to the Fayre of Tailtiu. Tailtiu was the queen of the Fir Bolg (an ancient celtic race) , the daughter of Mag Mor and the foster mother of Lugh. She died of exhaustion after the labor of clearing the lands of Ireland for cultivation, and in commemoration, Lugh held a festival for her. Two weeks prior to festival day, it was customary to climb a hill and survey the land before harvest. The festival then commenced, and lasted for four weeks – two weeks past the actual day.
Read more here