Gargoyles!

Etymology n. gar·goyle [gär-"goil] Middle English gargoyl, from Middle French gargouille; akin to Middle French gargouiller and from the same root word from which we derive gurgle, gullet, gully, gulp, gurgitation. Date: 13th century. 

Definition
A spout usually carved in the shape of a human, animal or demon, and connected to a gutter for throwing rain water from the roof of a building; although later examples - particularly in the Gothic Revival of the 19th century - served as merely decoration and served no earthly function. Today, they are associated with close cousins the grotesques, and Green Men.

Evolution
As early as the sixth century, Pope Gregory was instructing missionaries to respect the rituals of pagan worship. Wisely, the Church accepted these 'heathen' practices by incorporating them into the rituals of the Church (and not for nothing did Christmas later quietly replace the pagan Winter Solstice celebration.)

By the 12th century, however, the venerable St. Bernard of Clairvaux was ranting against the origins of the weird and irreverent carvings in his cloister. This was at a moment of time when The Catholic Church was now entrenched throughout the known world: 

St. Bernard, the grand master of organization who established the austere Cisterian order, was a stickler for dogma : What did monsters have to do with Christ dying for our sins? Why did stonecarvers continue to insist on this bizarre decoration? In his diatribe he finally posed the eternal question of administers everywhere: ...and what are they costing me?

A century later, gargoyles finally became the natural progeny of the grotesques St. Bernard railed against. 

Not only did they not go away, but those pagan grotesques were now serving as a primitive form of machinery: hollowed out then lined with lead, they were dubbed 'gargoyles' for the noise made as they violently spit rain water away from ledges and outcroppings.

The Last Gargoyle
Where is it? No one knows for sure, but an architectural historian might find it sculking on a relatively recent Neo-Gothic building. During the Victorian era, the Gothic Revival was a phenomenon in England that saw the reemergence of gables, parapets and - yes, real working gargoyles - that graced commercial stone buildings of the 19th century. It truly was the gargoyle's last hurrah, but the mania for the little beasties never really disappeared.

Washington National Cathedral, completed in the late 20th century, have featured them; and the Cathedral of St. John the Divine in New York which has yet to be completed. There's hope for yet another revival.

Until then, gargoyles and grotesques (wherever they have managed to survive) continue to fire our imaginations as they watch over us in cities throughout the world.

As it turns out, it may be our turn to watch over them.