The Kremlin is a world-famous complex of buildings, known as the eighth wonder of the world. The Palace Museum of China, Versailles Palace of France, White House of the United States and Buckingham Palace of the United Kingdom are also known as the five palaces of the world. It is listed by UNESCO as a world heritage for cultural and natural conservation. The Kremlin is Russia's secular and religious cultural heritage. It is not only the political center, but also the activity center of the Russian Orthodox Church in the 14th to 17th centuries A.D. The Kremlin is the palace of successive Russian emperors. It is now the office and administrative center of the President of Russia. The beautiful environment, including the Notre Dame Cathedral, the Angel Cathedral, the Church of Remembrance, the Bell Tower of Ivan the Great, and many other well-known Russian-style buildings. The Kremlin is the symbol of the Russian state, one of the largest buildings in the world, and a treasure house of historical, cultural and artistic monuments. Another peculiar phenomenon is that Emperor Putin's office is not as heavily guarded as he imagined. Compared with the situation in Zhongnanhai, Beijing, where troops are heavily guarded and Leichi cannot be surpassed, the Kremlin has always opened its doors to tourists from all over the world. As long as 300 roubles are paid for tickets, any visitor can enter and visit it, even from the President's office building. Just a few dozen meters away, the Kremlin is more open and friendly to the people.