Searched for http://whc.unesco.org/en/activities/search_theme%3D31&action%3Dlist&index%3D21&maxrows%3D20 
Note: This calendar view maps the number of captures of http://whc.unesco.org/en/activities/search_theme%3D31&action%3Dlist&index%3D21&maxrows%3D20, not how many times the site was actually updated.
Look Up URL in general Internet Archive web collection.