Uluru

Uluru was a portal to the hollow inner Earth. It was also a top-secret Chinese government research Facility.

When the Nannites recreated New Earth, they made it hollow. This was due to programming they were given in the Chinese Communist Party run factory in which they were built. They created Uluru to be the sole portal between inner and outer Earth.

Catalyst of the Great META War

When the Australian Government found out about China's secret research facility inside of Uluru in 201 B.B., they were understandably upset. They asked China politely to vacate the premises, to which China responded with several Nuclear Warheads. This led to a small conflict between Australia and China. The Combine, seeing that Earth's nations were weakened, decided to try to invade the planet during this time of weakness. This began the two-hundred year Great META War.

"I will walk on whatever land I want to walk on."- G-Man (Timefracture Alpha)