A bizarre villa built among what looks like piles of rocks and trees on top of a 26-storey Beijing apartment building faces demolition within 15 days, local authorities said. An order seen by AFP Tuesday, issued by a branch of the Chinese capital\'s urban management bureau, was posted on the door of a top-floor apartment in the block. It gave the owner of the structure -- which covers 800 square metres (8,608 sq feet) of rooftop -- to destroy it or give authorities an explanation within 15 days of Monday\'s date. Otherwise, a forced demolition will be carried out. But such threats are not always followed through in China, where law enforcement is sometimes selective. Access to the rooftop was blocked Tuesday by piles of plastic bags, cardboard boxes and other rubbish.  The debris has already proved an obstacle for the municipal personnel who would be charged with enforcing the order. \"The most difficult thing is that we can\'t get through the door,\" the Beijing News on Tuesday quoted one official as saying. Local media said the rooftop house was built over a six-year period by Zhang Biqing, the founder of a national chain of acupuncture clinics and a former member of a district-level political advisory body. At least two neighbours have moved out because of the construction work, while others complained of the noise and potential risk of the structure collapsing, reports said. Houses standing on top of multi-storey buildings are not unknown in China, where a rising property market is making land more and more expensive. A developer in central China built 25 luxury villas on top of a shopping mall, which became migrant workers\' residences after authorities declared them illegal, media reported earlier this month. Land disputes have become more frequent as officials and developers seek to cash in on the property boom, so that the government has reportedly forbidden housing demolitions without the owners\' consent.