What are the must-see attractions when traveling to Xi'an?

Please answer the question directly in concise language.

Xi'an, known as Chang'an and Haojing in ancient times, is the capital of Shaanxi Province, a sub-provincial city, the core city of the Guanzhong Plain urban agglomeration, an important national central city in western China?[1]?, and an important national scientific research, Education and industrial base?[2-3]?. Xi'an is one of the four ancient capitals of China?[4]?, a "World Historic City" determined by UNESCO in 1981?[2]?, and one of the top ten ancient capitals in the world selected by the US media. ?[5]?It is located in the middle of the Guanzhong Plain, bordering the Weihe River to the north, the Qinling Mountains to the south, and eight rivers that moisten Chang'an. It has jurisdiction over 11 districts and 2 counties, with a total area of ??10,108 square kilometers. It has economic and industrial highlands such as Xixian New Area, Shaanxi Free Trade Zone, and Xi'an Port. At the end of 2016, the permanent population was 8.8321 million, including an urban population of 6.4854 million [6-7].

Chang'an has been an imperial capital since ancient times. Thirteen dynasties including Western Zhou, Qin, Western Han, Xinmang, Eastern Han, Western Jin, Former Zhao, Former Qin, Later Qin, Western Wei, Northern Zhou, Sui and Tang were established here. All. It is an important birthplace of Chinese civilization and the Chinese nation, and the starting point of the Silk Road. ?[8]?Fenghao Capital, Qin Afang Palace, Terracotta Warriors and Horses, Han Dynasty Weiyang Palace, Changle Palace, Sui Dynasty Daxing City, Tang Dynasty Daming Palace, Xingqing Palace, etc. outline the "Chang'an complex". ?[9]?

Xi'an is China's best tourist destination and one of the country's civilized cities?[10]?. Two six heritage sites are included in the "World Heritage List", namely: The Mausoleum of the First Emperor of Qin and the Terracotta Warriors and Horses, the Big Wild Goose Pagoda, the Small Wild Goose Pagoda, the ruins of the Daming Palace in Chang'an City of the Tang Dynasty, the Weiyang Palace ruins of Chang'an City in the Han Dynasty, and the Xingjiao Temple and Tower. ?[11]?There are also Xi'an City Wall, Bell and Drum Tower, Huaqing Pool, Zhongnan Mountain, Tang Furong Garden, Shaanxi History Museum, Xi'an Forest of Steles and other scenic spots. Xi'an is also an important national science and education center, with seven "double first-class" universities including Xi'an Jiaotong University, Northwestern Polytechnical University, and Xi'an University of Electronic Science and Technology. ?[12]?

In February 2018, the National Development and Reform Commission and the Ministry of Housing and Urban-Rural Development issued the "Guanzhong Plain Urban Agglomeration Development Plan" to support Xi'an in building a national central city, an international comprehensive transportation hub, and Build an international metropolis with historical and cultural characteristics?[3]?[13]?.