Authorities are trying to learn who allowed a temple to be built atop a 21-storey residential building in Shenzhen, mainland media have reported. Surrounded by foliage, the temple has glazed golden tiles and traditional upturned eaves with carvings of dragons and phoenixes. Tight security prevented public access to the rooftop temple, with a fingerprint lock and cameras installed and dogs heard barking inside, the Yangcheng Evening News reported. "The ashes of burned offerings often drop down," it quoted an unnamed neighbour as saying. "It's privately built and has been there for years." A property agent near the compound said the top flat in the tower was worth 15 million yuan (HK$18.9 million) and all the building's residents were "either high-ranking officials or very rich people", it reported. "The owner must have some good relationships," it quoted the agent as saying. Authorities had failed to identify the facility's proprietor as investigators sent to the building had been unable to speak to its suspected owners. "Such a rooftop construction is very unlikely to get approval," Liu Minxing, a local official, told the paper. "We can almost be sure that it is illegal." Illegal constructions have come under public scrutiny on the mainland over the past weeks. A rooftop rock villa in Beijing sparked an outcry over the abuse of privilege and contempt for public safety by the country's rich, and authorities ruled houses on top of a shopping mall in Hunan could not be sold. Demolition work has begun on the rooftop villa built among what looked like a pile of rocks dotted with trees on top of a 26-storey apartment tower in Beijing, after neighbours complained and a blaze of media reports scrutinised the owner's business activities. Wealthy acupuncturist Zhang Biqing, the owner, said he had employed the same workers who built the structure for him six years ago to demolish it.