Midsummer !
The celebration of Midsummer's Eve (St. John's Eve among Christians) was from ancient times a festival of the summer solstice. Bonfires were lit to protect against evil spirits which were believed to roam freely when the sun was turning southward again. In later years, witches were also thought to be on their way to meetings with other powerful beings. The solstice itself has remained a special moment of the annual cycle of the year since Neolithic times. The concentration of the observance is not on the day as we reckon it, commencing at midnight or at dawn, as it is customary for cultures following lunar calendars to place the beginning of the day on the previous eve at dusk at the moment when the Sun has set.[clarification needed] In Sweden, Finland, Latvia and Estonia, Midsummer's Eve is the greatest festival of the year, comparable only with Walpurgis Night, Christmas Eve, and New Year's Eve. Ancient Romans would hold a festival to honor the god Summanus on June 20. In the 7th century, Saint Eligius (died 659/60) warned the recently converted inhabitants of Flanders against the age-old pagan solstice celebrations. According to the Vita by his companion Ouen, he'd say: "No Christian on the feast of Saint John or the solemnity of any other saint performs solestitia [summer solstice rites] or dancing or leaping or diabolical chants." Info:Wikipedia