The festival is primarily the Celtic fire festivity, midsummer representing the centre of summer, along with the shortening in the days on their gradual march to winter season. Midsummer is customarily celebrated on either the 23rd or 24th of June, although the longest morning actually falls on the Twenty-first of June. The importance of the day to our ancestors can be monitored back many thousands of years, and many gemstone circles along with other ancient monuments are usually aligned towards the sunrise on Midsummer's Day. Essentially the most famous place is that in Stonehenge, where the sun rises in the heel natural stone, framed by the giant trilithons about Midsummer morning.