The construction of what chinese landmark caused several large cities to disappear?

the construction of what chinese landmark caused several large cities to disappear?

1. The #GreatWall the Longest Defensive System in the World,
2.The Forbidden City 9999 Rooms for 24 Emperors,
3. The Terracotta Army First Emperor Qin's Buried Battalions,
4. The #PotalaPalace Masterpiece of Tibetan Architecture,
5. The Summer Palace China’s Largest Imperial Garden,
6. The #MogaoGrottoes a Holy Land of Buddhist Art,
7. The Three Confucius Sites

The Great Wal,The Forbidden City,The Terracotta,The Potala Palace Masterpiece,The Summer Palace Chin,The Mogao Grottoes a Holy Land,The Three Confucius Sites,