Mexico City, has always been thinking about where to come. Before coming, many people said that it was not safe, and advised me to report a group. In the end, I was still free to come. The first impression is that people are more dense. Mexico City is only one-tenth the size of Beijing, but with a population of more than 22 million, it is one of the most crowded cities in the world. After landing, I came to the Constitution Square, which is located in the center of the old city. The square is surrounded by old buildings such as the National Palace and the Capital Cathedral. First feeling, I really like it.