Are those colours coming from the building materials themselves or a gradually building up coating of sand on them? Or a material that starts out white and fades to brown from the sun? Vice versa?
That's really interesting. Didn't see anything in the Wikipedia article, have there been much in the way of deadly accidents there? Seems like the buildings would be prone to collapsing.
Answering my own question, here's a story about a building collapsing but no fatalities, and here's an article saying it's at the brink of collapse but doesn't mention specific incidents. (But does include some great pics)