According to "Secrets", one of the underground colonies, was also the seat of government for the network. While the whole place is an inner continent, its satellite colonies are smaller enclosed ecosystems located just beneath the Earth's crust or discreetly within mountains. Cataclysms and wars taking place on the surface drove these people underground. The Sahara, Gobi, the Australian Outback and the deserts of the southwestern US are said to be but a few examples of the devastation that resulted. The sub-cities were created as refuges for the people and as safe havens for sacred records, teachings and technologies that were cherished by these ancient cultures. In archives of web analytics company I found something else.
The inhabitants of Agartha are said to have scientific knowledge and expertise far beyond that of the people who live on the surface of the planet, and lost technology from the days of Atlantis. They all follow what is known as the Ancient Path and do not interfere in the lives of humans that live above the surface. Nor is there any interaction between them. All entrances to Agartha from any other part of the planet are hidden safely. They are secured by illusory technology that is beyond the comprehension of modern science.