Seen in PhuKhong..... Chang'an is an eco-tourism in the scenic population Trang An Ninh Binh province by the Government of Vietnam national relic is especially important. It is also known as South of the ancient capital of Hoa Lu , the system of limestone mountains geological age about 250 million years, over a long period by the alteration of the earth, the climate, the sea, Sea quit carrying the hundreds of valleys, caves, lakes and swamps.