Indeed, this is one of the many outstanding Chinese masterpieces, added to over many centuries. It was a most thrilling experience to visit Longmen.
My first visit to Mainland China was in 1980, and I have returned on a number of occasions.
I served as a "Foreign Expert" teaching English and Western Civilization at the Normal College of Foreign Language in Beijing in 1987-8. The Foreign Experts Bureau was based at my residence hotel, the Friendship Hotel in Beijing. Not only did they 'watch over us', they were there to assist us in many ways. About every third week they organized a weekend visit to historic sites. I visited twenty-one provinces that year, usually for less than US$20 a weekend, everything included. Those were the halcyon days of China before the tragedies of 1989.
My visit to Longmen was in May 1988, and there was considerable time to visit the various caves. It was somewhat understanding, though disappointing, to see all of the vendors and to see people climbing among the statues. I understand that the vendors have been removed from the immediate area. That visit has remained one of the highlights of my numerous visits to China.
My interest in Chinese architecture developed greatly as a result of these tours, and it led to my extended participation in a co-operative web photo venture on "Asian Historical Architecture." The site includes almost fifty photographs of the Longmen Grottoes, plus a long essay (plus the Yungang Grottoes, and about 10,000 images from many other parts of Asia): http://www.orientalarchitecture.com/ >China>Luoyang>Longmen Grottoes.