Nuzul Al-Qur’an is an Islamic holiday that commemorates the revealing of the first verses of the Qur’an to Muhammad the Prophet. It is celebrated on the 17th day of the month of Ramadan. Nuzul Al-Qur’an is a public holiday in Brunei and some Malaysian states and federal territories.
Olympic Day is an annual celebration that commemorates the formal establishment of the International Olympic Committee on June 23, 1894. It was officially created in 1948 as a sort of birthday of the Olympic Movement.
The evening of June 23 is known as St John's Eve in some countries. It is the eve of celebration before the feast of Saint John the Baptist. The holiday is also strongly connected with Midsummer, the celebration of the summer solstice.
United Nations Public Service Day is an official UN observance held on June 23 each year. It was designated in the resolution 57/277 of the UN General Assembly issued on March 7, 2003 and has been celebrated annually ever since.
International Widows' Day is an official United Nations observance held on June 23 each year. It was established by the UN General Assembly in December 2010, and the first celebration occurred in 2011.