On this day, 40 years ago, on August 19, 1985 (July 4, 1985 lunar calendar), the Tropic of Cancer Tower was completed in Guangzhou. The Tropic of Cancer is an important geographical indication line like the equator. It is called the Tropic of Cancer at 23 degrees 27 minutes south latitude and the Tropic of Cancer at 23 degrees 27 minutes north latitude. The Tropic of Cancer is the southernmost and northernmost boundary where the sun's direct rays move throughout the year. During the winter solstice, the sun shines directly on the Tropic of Cancer, and during the summer solstice, the sun shines directly on the Tropic of Cancer. The area between the two lines, where the sun shines directly twice a year, is called the tropical zone; beyond the two lines are the temperate and cold zones. The Tropic of Cancer is the dividing line between the tropical and temperate zones. In order to display the civilization of the country, popularize scientific knowledge and promote the development of tourism, the practice of building monuments and towers In our country, the Tropic of Cancer passes through the four provinces of Yunnan, Guangxi, Guangdong and Taiwan, which is more than 2,000 kilometers long, of which the Tropic of Cancer in Guangdong accounts for about one-third of the total length of the four provinces. The Tropic of Cancer Tower, completed in Taiping Field, Conghua, Guangzhou on August 19, 1985, is the largest and tallest tower on the Tropic of Cancer in our country. This sign tower is 23.5 meters high, consistent with the latitude figure of the Tropic of Cancer. The whole tower integrates architectural craftsmanship, painting and sculpture. The tower body is shaped like a rocket, pointing directly into space; the top of the tower is a hollow copper ball with a diameter of 120 cm, symbolizing the scorching sun. The tower body is hollow, and wings float out on all sides, indicating the four directions of southeast, southwest, northeast and northwest respectively; the base of the tower is conical, symmetrically equipped with four arches, facing east, west, south and north. Visitors enter the tower to visit, standing in the center of the four gates at the bottom of the tower, they can peek into the sky from the center of the tower and the round hole in the copper ball. The front of the tower is engraved with six large characters of "Tropic of Cancer Sign". The sign tower can be enjoyed by tourists and can make people appreciate the warm and warm areas on the north and south sides of the tower body. If it happens to be at 12:26 noon on the day of the summer solstice, the sun is hanging on the top of the tower, and people stand in the tower, and they cannot see themselves. At the moment when spring and summer alternate, time and space are cleverly combined, people can appreciate the taste of the earth moving diagonally between the zodiac and the return of the sun between the Tropic of Cancer. The Tropic of Cancer passes through about 30 countries and regions, but most of them are desert areas or mountainous areas far from towns, which are not suitable for building landmark towers. There are a total of five Tropic of Cancer landmark towers in the world in China, located in Guangzhou, Shantou, Fengkai and Chiayi and Hualien counties in Taiwan Province.