The use of "Phoenix Nirvana" to describe Warsaw is the most suitable city. Warsaw, which was almost razed in World War II, has now become a vibrant modern city. Without reading Polish history, it is difficult to understand the complex emotions of people facing Warsaw's Old City. The World War II brought Poland a devastating and declining population, and the city of Warsaw was destroyed in this war. Fortunately, on the eve of the outbreak of World War II, the teachers and students of the Department of Architecture of the Warsaw University made surveys and records of the main blocks and important buildings of the Old City, and hid the drawings and materials into the caves. After the war, the Poles built a Warsaw old town on the ruins exactly the same as before the war. Not only maintained the style of the ancient city of the Middle Ages, but also built a new urban area, exceeding the scale and level before the war. During the reconstruction process, the work of protecting and repairing historical monuments was paid special attention. More than 900 historical buildings in the pre-war city were repaired and decorated, and those former palaces, churches, castles, etc. Its spectacular.