I saw my first piece of Julie Mehretu's art work at the MET a few years back. It was called "Empirical Construction, Istanbul." I remember looking at it for such a long time, and it stuck with me. I did more research on her, and I was enamored by her work. The lines, the colors, the movement ... the fact that they show direction and are based off of something, not empty strokes.
A quote from her about her work:
"I think of my abstract mark-making as a type of sign lexicon, signifier, or language for characters that hold identity and have social agency. The characters in my maps plotted, journeyed, evolved, and built civilizations. I charted, analyzed, and mapped their experience and development: their cities, their suburbs, their conflicts, and their wars. The paintings occurred in an intangible no-place: a blank terrain, an abstracted map space. As I continued to work I needed a context for the marks, the characters. By combining many types of architectural plans and drawings I tried to create a metaphoric, tectonic view of structural history. I wanted to bring my drawing into time and place."
To find out more about Julie Mehretu and her work, check out her artist's page here: http://www.mariangoodman.com/artists/julie-mehretu/