Perhaps most excitingly, it has the Terracotta Warriors.
Our visit to these was certainly one of the highlights of the tour. The sight of the legions of unearthed warriors, and the pits with broken bodies still to be pieced together, was incredibly moving.
Even more moving, though, was the Xi'an orphanage. This has relatively good facilities, and warm, responsive carers, and is certainly not one of the terrible institutions that hit the news years ago, but the rooms full of small children, many with disabilities, who have been abandoned by their parents for a variety of reasons are a sobering, heart-rending place to be.
This orphanage has an accommodation building where foster families live, who take some of the children home for nights and weekends, which seems a progressive idea. Some of the children will be adopted, nearly all by westerners. Some will never find a family and will move on to an adult orphanage at 16.
Xi'an is certainly a fascinating place. We went to the Great Mosque and the Moslem market nearby, and had nursery names written in Chinese characters by a backstreet calligrapher. We also visited a Chinese medicine market, with remedies on sale including scorpions, ginseng and some things that shall remain nameless.
On to the south west and Guilin with its spectacular mountains.