Had the building sprouted massive wings and uprooted itself? They wondered, and pointed. Perhaps it was the kind of anomaly that researchers would classify as "other" in charts devoted to probable natural disasters for the region.

Sometimes the artists over at ConceptArt.org organize a truly inspired challenge, and the call to create a "Winged Fortress" was one such challenge. Here are some of the most amazing concepts that artists came up with. See all the entries in the challenge via Concept Art.