
In the heart of Hong Kong, a former British colony, sits an unmistakable symbol of the city's Chinese rule, now in its 18th year: The barracks of the People's Liberation Army (PLA).

Every year, on July 1 -- the anniversary of the return of Hong Kong to Chinese control, the PLA allows some of the city's residents to look inside the secretive base.

It's an unusual military display next to Hong Kong's typically placid harbor.

Soldiers perform a drill not far from the International Commerce Center (ICC), the city's tallest skyscraper.

Around 6,000 PLA troops are believed to be stationed throughout multiple bases in Hong Kong. So far, they have never been sent into action in the territory.

Hong Kong's special status as a Chinese territory with a semi-autonomous government has been a constant source of tension in the city. Surveys show fewer residents, especially young people, identify as Chinese.

PLA soldiers here are from mainland China, and only a few speak Cantonese -- the preferred language for many Hong Kongers. Hong Kongers are not permitted to serve in the PLA.

Typically, soldiers here keep a low profile: They never come out onto the streets of the city, and there's minimal interaction with the local population.

Hong Kong's governing Basic Law stipulates the garrison "shall not interfere in the local affairs of Hong Kong," but the Hong Kong government may request assistance from soldiers during emergencies.

For many Hong Kongers, the sight of PLA vehicles still evokes memories of the 1989 Tiananmen Square crackdown, when Chinese soldiers opened fire on student protesters in Beijing.

During last fall's massive pro-democracy street demonstrations, known as "Occupy'' or the "Umbrella Movement," protesters feared China might deploy its troops to restore order. But that never happened.

For many Hong Kongers, the PLA's annual Open Day is their only chance to see real military equipment.

Soldiers watch as children play with machine guns -- not loaded, of course.

Mainland Chinese visitors also come to Hong Kong every year for the special event, which does not happen in China. "The army is still a bit mysterious to us, so it is good for us to know more," one visitor told CNN.

Firearms are tightly controlled in Hong Kong and China -- ownership is basically restricted to police, military, and security firms.

China's warships occasionally make appearances in Hong Kong's Victoria Harbor.

The inside of China's military vessels are lined with patriotic images and slogans.

While troop numbers remain constant, the garrison's personnel are frequently rotated in and out of Hong Kong.

Hong Kong residents who attended the event expressed optimism about the city's ties with China. One told CNN the relationship should be that of a "father and children," or "lips and teeth."