Why didn't Elon Musk mention where colonists will live on Mars?

During his hour-long announcement of the Space X Mars colonization plan, CEO Elon Musk didn't say where exactly Martian colonists will live once they arrive on the planet — and how exactly they'll survive given the harsh environment.
Musk seemed particularly unconcerned about solar radiation. "The radiation thing is often brought up, but it’s not too big of a deal," he says. There is a "slightly increased risk" of cancer, he says, and there will probably be some sort of shielding. He