The first city of a million was built two thousand years ago. But how did they make Ancient Athens and Rome work without petrol, gas or electricity?

Overview

Rome, 2000 years ago was the world's first ancient megacity. In a world where few towns had more than ten thousand inhabitants, more than a million people lived in Rome. How did they manage without all the technologies of our modern cities? How did they bring in enough food to sustain the population? How did they house them? How did they maintain law and order? How did they make this city work?