Samhain symbolizes the transition from summer to winter. Beginning around October 31/ November 1, it is this time of year that the veil between our world and the 'otherworld' is the thinnest. Burial mounds, or Sidhe, (depicted in picture) were built so that souls could easily cross through worlds. There could be no war till the festival of Beltain and food was carved out to ward of unwanted spirits. This festival is still celebrated today through Halloween and Jack-O-Lanterns.