A self-made billionaire is reconstructing the capital's ancient city walls - in miniature and in sandalwood. Deng Zhangyu reports.

Those born before the 1950s remember Beijing's walls as the "city's necklace".

Most of the greatest pearls of this historical treasure have been destroyed but are being reconstructed - in sandalwood, at a tenth of their original size.

Sixteen miniatures will be created, and the first - Yongding Gate, at the south of Beijing's city axis - has been unveiled to the public at Beijing's China Red Sandalwood Museum.

"Younger people don't know what Beijing looked like before," the project's director and museum's founder Chan Laiwa says.

The 71-year-old descendant of a Manchu Yellow Banner clan family spent her childhood in Beijing's hutong (alleys) and grew up playing on the city walls.

She became a self-made billionaire and an art and culture advocate who set out to produce a replica of Beijing's city gates out of red sandalwood and ebony.

Both are costly materials. Red sandalwood trees require centuries to mature while ebony comes from semi-fossilized wood that has lain at the bottom of the great rivers for thousands of years.

"It's hard to find red sandalwood," replica producer, Fuwah Furniture Ltd manager Chen Peilin says.

Chen says ebony is so similar in color to the gates' grey bricks that no paint is required.

The production team employs about 120 designers, ancient architecture experts and craftspeople.

They started work in 2011, and it took them more than a year to produce the maiden model of Yongding Gate, Chen says.

"There are few documents and photos of Beijing's city walls," Chen says.