What started as a small leak of weaponized nano quickly grew in size as it consumed and reshaped every material it touched in the city. Eventually it towered over the wreckage in an oozing wave.
Before the molecule containment devices were put in place, it almost looked like it was trying to stand up, to take on the shape of the humans whose bodies it had devoured along with everything else.
Luckily, however, it was brought to a standstill by the plasma bursts from a grid of quickly-erected energy conduits.
Some areas of the city became so unstable that they were flooded and turned into a harbor.
Eventually, over time, the now-frozen wave of reconstituted steel, concrete, flesh and parks began to decay. But its body and the city around it never grew healthy, normal plants again - somehow the area remained tainted, yielding only mutants.
I've often read about the supposed "gray goo" phenomenon, where self-replicating nano machines go wild, deconstructing everything in their path. Until I ran across concept artist Giacomo Costa's work, I'd never seen images that evoked what that might look like. Created over the past five years, these paintings manage to be documents of a nano plague without ever intending to evoke anything other than a strange architecture of the future.
Costa's surreal landscapes are often post-apocalyptic, and you can see more of his amazing work in his online gallery.