It's ironic, I suppose, that to get there I had to drive for many miles on dirt road, but at the destination there was a modern federal building museum.
Chaco itself was like a group of small cities spaced apart, with medieval quality stonework, of maybe three different kinds. A thousand years ago or so, it acted as the center of a major trade route and banking center, all the way from New England to South America.
A currency of the time was chips of turquoise, and they found a "vault" with tens of thousands of chips in it.