Oh, you haven't heard of Kowloon Walled City? It was a ungoverned piece of land in Hong Kong, but also the most densely populated spot in the world. 33,000 people lived on 2.6 ha in 300 buildings. The height of the illegal built houses was limited to 14 storeys. - Because it was located in the final approach to the only runway of Kai Tak Airport. One of the busiest airports in the world at the time. Including an extremely difficult approach - over Kowloon Walled City. https://en.wikipedia.org/wiki/Kowloon_Walled_City