Seen as the most mysterious culture wonder within China, this cliff cave group was home to mysterious ancient people lived - a historic site of 1,000 years old.

It sits in a tranquil gorge in the northwest of Beijing. The caves were made on a precipitous cliff by a group ancient people who were not accounted in any history books. There are 117 caves in all.

The man-made stone rooms were arranged one by one on the steep cliff wall in the gorge. They are rectangles or squares in shape. The biggest one is about 20 meters in length and the smallest one is only 3 to 4-metre-long. Some caves are made up of one room, some several rooms. Some rooms are parallel, some rooms are divided into two stories. Among them there is a big two-stories cave flanked by small rooms and columns. It may be a place for material or sacrifice and to be called 'Guan Tangzi'.

It is supposed to be constructed in Yuan Dynast or Wei, as the home of gangsters, or the camp of army, or the shelter to escape the war...no any proven evidence or record that can identify those ancient Mysterious to those unique cliff caves