Ruins of secret passages on Great Wall discovered

TIANJIN: Ruins of over 130 hidden doors on the Great Wall, one of the world’s great wonders, have been recently unveiled through close to centimeter-resolution continuous shooting, said a research team on the Great Wall’s defense system on Wednesday.
Based on further picture analysis and field trips to the secret doors, the team found each hidden door designed to be highly compatible with the local topography. In history, those secret passages were for scouts to pass through, while some were built as channels for communication between inside and outside of the Great Wall, or for trade and commerce in ancient times.
According to some official documents dating back to the Ming Dynasty (1368-1644), nomadic tribes were allowed to use such secret gates for grazing their cattle between northwest China’s Qinghai and Hetao, a region with abundant water and grass resources at that time. Such practice is also evidenced by some large secret doors that could allow two horses to pass in both directions, said Zhang Yukun, a professor from Tianjin University, also head of the research team.
“These all help prove that the Great Wall is not completely closed, but ‘open’ in order,” Zhang added. –Agencies