"The 2016 theme for the ICOMOS International Day on Monuments and Sites celebrated on 18 April is: The Heritage of Sport ..."

http://www.icomos.org/en/what-we-do/focus/18-april-international-day-for-monuments-and-sites

18 April - Ideas for celebrating (Link)
http://www.icomos.org/en/what-we-do/focus/18-april-international-day-for-monuments-and-sites/ideas-for-celebrating