I love this work, I love the scale, and I love the process.
I feel as if I have a tiny something in common with Ms Mehretu; the calligraphic quality of her work is something I understand, although in my own case I work on a very different scale. It's a tad like speaking the same language. Her painting above measures 27 by 32 feet.
Ms Mehretu is an American of Ethiopian origin. This painting, that she is seen working on above, is one of two that are apparently the worlds largest. I think they're entitled HOWL, eon (1 and 2).
If you happen to be in San Francisco, you can now see both works at the Museum of Modern Art. Otherwise you could consult Google Images; an example below.