Cultural memory façade

All the posters, advertising, banners, city lights of concerts, events, products, of Christmas - are replaced every month, and there is no more evidence of the past events in the city.
Idea is about to cover a huge wall of some office building with posters every month, so people could remember what was the major events in their cities. Wall could be in some public space, lots of people there. Selection of major events poster would be on curators of arts, business and politics.
With this facade people could remember where they been 4 month ago