The Hong Kong Frontier Closed Area was orginally set up to stop illegal immigrants, smugglers and spies.
Cold War relic: Hong Kong's hidden green zone —
The Hong Kong Frontier Closed Area was orginally set up to stop illegal immigrants, smugglers and spies.
AFP/Getty Images
Hong Kong's green border zone is separated from Shenzhen by the Shenzhen River seen in this file picture from 2004.
Hong Kong's hidden green zone —
Hong Kong's green border zone is separated from Shenzhen by the Shenzhen River seen in this file picture from 2004.
SAMANTHA SIN/AFP/Getty Images
Some residents within the Frontier Closed Area want the right to develop their properties.
Hong Kong's hidden green zone —
Some residents within the Frontier Closed Area want the right to develop their properties.
Getty Images
The Mai Po Nature Reserve is one of the few pristine areas left in the Hong Kong SAR.
Hong Kong's hidden green zone —
The Mai Po Nature Reserve is one of the few pristine areas left in the Hong Kong SAR.
AFP/Getty Images
Wetlands within the border area are an important seasonal staging post for migratory birds.
Hong Kong's hidden green zone —
Wetlands within the border area are an important seasonal staging post for migratory birds.
AFP/Getty Images
A new fence along the border with Hong Kong and China has obviated the need for the Frontier Closed Area.
Hong Kong's hidden green zone —
A new fence along the border with Hong Kong and China has obviated the need for the Frontier Closed Area.
Getty Images
The Frontier Closed Area was put in place during the Cold War as relations deteriorated with China during the Korean War.
Hong Kong's hidden green zone —
The Frontier Closed Area was put in place during the Cold War as relations deteriorated with China during the Korean War.