We are committed to the construction of a digital world of three-dimensional cities. This is not limited to the current cities but also includes great cities that have appeared in history, such as Chang’an and Rome. We also explore people’s cities in the unknown world, such as Atlantis. Of course, we also explore how to construct the future world of mankind. It has not been realized as soon as possible. But it is different from the virtual cities in movies or games. We will explore a way to build these cities scientifically. Here we issue an invitation and hope you can join in!