Visitors to Liu Dalin's private museum would have difficulty locating the premises if not for a sign near the door that is discreetly removed as soon as the tour is over.
A sex museum on the outskirts of Shanghai, Mr Liu's hideaway not only holds secrets to China's sexual mores but is testament to the more liberal attitude of ancient China.
'Our ancestors were not as conservative [about sex] as we imagine them to be,' Mr Liu said. 'Though they worked hard, they also knew how to enjoy life and possessed a rich knowledge about sex.' The 66-year-old former sociology professor developed an interest in China's sexual history after spending years researching family and marital issues. What he discovered made him realise how many marriages deteriorated these days simply because of unfulfilling sex. In 1989, he surveyed 23,000 people in rural and urban areas in 15 provinces about sexual behaviour and discovered that most were 'feudal-minded' about sex - a legacy of the repressive Ming and Qing dynasties that he believes continues today.
'[In our society] divorced women and rape victims are tainted,' he said. 'Couples over 60 years old are too ashamed to have sex. A woman who loses her virginity before marriage is scorned by society. Sex must only be initiated by the husband. Homosexuality is a crime.' To gain a deeper understanding of sex and its inhibitions in modern China, he read volumes of books on sex in ancient Chinese and visited historical sites in Inner Mongolia, Xinjiang and Ningxia, where he found sex-related sculptures and rock carvings.
In ancient times, people attributed what they could not understand - such as their need for sex or where babies came from - to supernatural forces, he said, which gave rise to various forms of worship, sex included.
'People believed that sex worship, which included the worship of sex organs, sexual intercourse and reproduction, would bring bumper harvests and good fortune,' Mr Liu said.