Grottoes, as shrines for Buddha worshipping, were popular in the early period of Buddhism. These fall into two categories: those used by monks purely for self-cultivation, which feature altars for Buddhafor worshipping by the general public.

    Ancient Chinese began building grottoes shortly after Buddhism found its way into China, and most grottoes that have been preserved to this day are found in Xinjiang, Gansu and Shaanxi of northwest China and Shanxi, Henan and Hebei in northern China. Like the religion itself, grottoes eventually became a part of the Chinese culture. In Dunhuang of Gansu and Datong of Shanxi, there are grottoes with carved pillars of stone in the center. These are invariably in the shape of Buddhist pagodas or Buddha images, with altars carved on them for worshipping.

    Grottoes built in later centuries feature carved Buddhist images on the wall facing the opening. But there are also grottoes that have Buddhist images on all the three walls, and round the images are colorful patterns of auspicious animals and plants, obviously to create the kind of environment which, Buddhist followers believed, was characteristic of the "Land of Buddha" or the "Land of Utter Happiness". Most grottoes found in China are of the second category. worshipl~ing on the three walls, and those with a Buddhist tower inside.

    Some grottoes are built on steep cliffs. Here is a quotation from an ancient Chinese author: "Half way from the blue sky, on those precipitous cliffs, one thousand caves are dug into rocks in which ten thousand altars of Buddha are worshipped. Though done with human labor, these arouse admiration for divine workmanship." Grottoes in such a natural environment seemed to be designed to hold Buddhist believers in awe of the mysterious "Land of Utter Happiness" and thus cement their devotion to Buddha. It won't be difficult to imagine that building of such grottoes was not an easy task in ancient times when everything had to be done by hand. One example is the Fengxian Temple, the largest Buddhist grotto in the area, which features a 17-meter tall Buddha statue carved on a hill. To facilitate the carving of the statue, workmen toiled for three whole years to cut open the hill and prepare the work site that was 41 meters deep into the hill and 36 meters wide. The first few grottoes on Mt. Maiji in Tianshui, Gansu Province, were built in the fourth century, and more were built in the following centuries. Altogether, some 200 grottoes are counted on the mountain, and most of the grottoes are on cliffs up to 100 meters high.

    A web of plank roads built on the surface of Mt. Maiji link the grottoes. The plank roads, somewhere between one and 1.5 meters wide and 800 meters in total length, are in 20 sections at different heights. In building a blank road, the first step was to hammer horizontal beams into the mountain, the distance in between the beams being half a meter to several meters, depending on the circumstances. When workmen were sure that the beams were fast enough, they would nail wooden planks to the "roadbed". The last step was to build the protective railings along the road. Building of the plank roads was already difficult enough, let alone the digging of the caves.

    Grottoes are invaluable not only for their importance as Buddhist structures, but also as treasure houses of art. Inside grottoes we find large quantities of ancient Chinese carvings, clay sculptures and murals. Though on Buddhist themes, these artworks constitute a panorama of life in the real world. On murals found in the Dunhuang, Longmen and Yungang grottoes, for example, ancient buildings of all kinds are pictured - city walls, palaces, gardens, temples, marketplaces, streets, residential buildings, bridges, pavilions, towers, and so on, not only their physical outlooks but also their structures in minute details. These are of immense value to studies of ancient Chinese architecture. Moreover, grotto sculptures and murals feature prominently in the history of China's traditional fine art.