Construction of Longman Shiku (Dragon Gate Grottoes), one of three major grottoes in China, began in 494, but it was not until the Sui and Tang dynasties that it acquired the scale as we see it today. Among Longmen's wealth of world-famous treasures are flying Apsaras as well as fine works of Chinese calligraphy, represented by the "20 Longmen Calligraphic Samples'' (20 pieces of calligraphy deemed perfect and correct representatives of the times they were created in). Enshrined in a total of 2,100 cave-temples are 3,600 stone inscriptions and over 100,000 large and small Buddhist statues. The 17-meter-high statue of Vairocana in Fengxian Temple is the most representative of the trove.