Far beneath the lush landscape of southern China, a sprawling subterranean laboratory aims to be the world's first to crack a deep scientific enigma.

China has emerged as a science powerhouse in recent years, with the country's leadership pouring billions of dollars into advanced research.

Its latest showpiece is the Jiangmen Underground Neutrino Observatory (Juno), a state-of-the-art facility for studying the minuscule subatomic particles.

The project is an "exciting" opportunity to delve into some of the universe's most fundamental -- but elusive -- building blocks, according to Patrick Huber, director of the Center for Neutrino Physics at the American university Virginia Tech, who is not involved in the facility's research.

International media was recently given a tour of the observatory in Kaiping, Guangdong province, organised by the Chinese Academy of Sciences, the country's national science agency.

The lab is reached by a funicular train that travels down a tunnel to a cavern built 700 metres underground to limit radiation emissions.

Inside stands the neutrino detector, a stainless steel and acrylic sphere around 35 metres in diameter, crisscrossed by cables.

"No one has built such a detector before," Wang Yifang, Juno's project manager and director of the Institute of High Energy Physics, said as workers in hard hats applied the finishing touches to the gleaming orb.

"You can see from the scale, it was technologically complicated," Wang said as he waved a laser pen over different parts of the installation.

Started in 2014, Juno has cost around 2.2 billion yuan to build and is due for completion next year.

It aims to solve a fundamental physics puzzle about the particles' nature faster than scientists in the United States, a world leader in the field.

Its research could also help us better understand planet Earth, the Sun, and other stars and supernovas. (AFP)