China must find the balance between a growing tourism industry and protecting their sites

In a quiet corner of southern China's Pearl River Delta, hundreds of abandoned watchtowers dot a landscape of water-logged rice paddies, lush bamboo groves and ancient villages.

Bristling with battlements and turrets, the ornate towers were built by families and villages in need of protection during the late 19th and early 20th centuries when much of the country was controlled by warlords and banditry was rife.

Now a UNESCO world heritage site, these days the Kaiping watchtowers, or diaolou as they are known locally, face a threat of a different nature -- the incredible boom in Chinese tourism.