Ask LW: What are some well-designed institutions?

I’ve been reading “Microeconomics: Behavior, Institutions, and Evolution” and it’s awesome. It’s inspired me to ask LW:

Can you give me an example of a good institution? Why is it a good institution? What caused it to become a good institution?

It can be an institution at any level of organization. If you’d like to talk about why your brain is a good institution I’d like to hear about that. Or the country of Burma. Or the free market. Or the Catholic memeplex. Whatever you wish.