What does a picture falling of the wall mean?
Perhaps you are experiencing an earthquake!
Rush to open areas away from buildings and braking glass, or if indoors go under door frames or strong tables.
On the other hand, perhaps the nail holding it up has just loosened over time and it fell off.
Not all naturally occurring phenomenon can or should be interpreted as signs or omens. That said there is a widely held superstition that says a picture falling from the wall (with no reason) is a bad omen, possibly of an upcoming death in the household. - however it is said the glass must break for the omen to be true.
Not all naturally occurring phenomenon can or should be interpreted as a sign or omen. Unless the picture was of someone specific and of significance to you personally I would not take it too seriously. That said there is a superstition that says a picture falling from the wall, for no apparent reason is the omen of an imminent death, however, the glass in the picture must shatter for the omen to be believed as…
It likely means that the picture was not properly secured to the wall. ___ In terms of otherworldly meaning, it probably doesn't mean anything serious. Most reports of pictures/paintings falling to the floor during paranormal experiences are just a ghost trying to show people that it is there, not a particular vendetta against a specific person. I would attach it more firmly to the wall, and see if anything else happens specifically to that picture…
Assuming the question really is "Who took the first picture of the entire Great Wall of China" I do not see how this is possible, given the length of the wall. It would be possible to take a picture of the entire Great Wall from a low-orbiting satelite or space shuttle, except portions of the wall no longer exist, so it would not be the "complete" wall.
The safest way to mount a picture is to always have another person with you to help hold the picture or the ladder. If the picture weighs less then 20 lbs then a standard nail in the wall will be sufficient to hold the picture. However, if the picture is heavier then one would want an anchor in the wall instead of the nail.