Dracula silhouette, which comes alive at night
London marketing department “BBC Creative” installed billboards timed to coincide with the release of the television program.
In the daytime, wooden stakes with imitation of bruises can be seen on the billboard.
Bottom, under the billboard, there is a glass box with a stake and the inscription “Smash it if vampires appear”.
But in the dark, with the lights on, due to the shadows of the stakes, the profile of a dracula is formed.
This can be clearly seen on the attached gif. Not a standard idea, but difficult to implement.