It's absolutely nuts. I had a population of around 36k, all of the facilities that could be built, and it was garrisoned with a full 19 units plus a governor. The squalor was measuring in at 122% of unhappiness.

The only way I managed to handle it, was to remove all my troops and governer, let them revolt, reoccupy it, then slaughter the inhabitants down to a manageable size.

Not only is this historically inaccurate, but it's also plain old stupid. Has anyone made a mod to decrease squalor yet?