Historically, gargoyles were spouts in the sides of walls, to which water was routed to be shot away from the structure. This was important, because unchecked rainwater would cause water damage; discoloring walls, or even destroying them. In the modern world, however, gargoyles are not as important, as stone is no longer our primary building material. Because of this, the word have evolved to take on a new meaning: a carved figure on a building. In my city, we have some faces carved into the wall of a building, meant to resemble the appearances of various council members of that day. They were actually quite a source of controversy back in the day, with newspapers slamming them as "meaningless heads which stand out boldly in all their ugliness."
Banner image property of Owen Cyplops