The lighthouse is a high tower-shaped building. The lighting equipment is installed on the top of the tower. The location should be prominent, and attention should be paid to its specific architectural shape, which is easy for ships to distinguish and becomes one of the highest points of the port. Because the surface of the earth is curved, the tower body must have sufficient height so that the light can be seen by long-distance ships, and the general sight distance is 15-25 nautical miles. However, the light should not be too high to avoid being obscured by clouds and fog from high places. According to the size of the lighthouse and the characteristics of the location, the lighthouse can be guarded or unguarded, and important lighthouses should be guarded.