They are probably the most famous ox, tiger, monkey and pig heads in China, and befitting their status as national treasures the bronze sculptures are under round-the-clock surveillance in Beijing.

The curator of the four heads, which spent more than 150 years abroad after British and French soldiers looted them from Beijing's Yuanmingyuan Park, or the Old Summer Palace, in 1860, is Poly Culture Group Co (Poly Culture), which is at the forefront of China's culture industry.

The current home of the four heads is the Poly Art Museum on the ninth floor of New Poly Plaza in Beijing, China Poly Group Corporation's headquarters, a glass-clad skyscraper.