Hıdırellez or Hıdrellez (Turkish: Hıdırellez or Hıdrellez, Azerbaijani: Xıdır İlyas or Xıdır Nəbi, Crimean Tatar: Hıdırlez, Romani language: Ederlezi) is celebrated as the day on which Prophets Hızır (Al-Khidr) and Ilyas (Elijah) met on the earth. Hıdırellez starts on May 5 night and falls on May 6 in the Gregorian calendar and April 23 in the Julian calendar. It is celebrated in Turkey  and throughout the Turkic world. It celebrates the arrival of spring and is a religious holiday for the Alevi as well. Đurđevdan is the Christian variety of this spring festival throughout the Balkans, notably areas which had become under the control of the Ottoman Empire by the end of the 16th century.
There is couple of activities and concerts will be at Heybeliada