There are many “centers of the world.”
For example, Zhōngguó is the most common name for China. The first character zhōng (中) meaning “central” or “middle,” while guó (国) means “state” or “kingdom,” so Zhongguo is the “Middle Kingdom” or “Central Kingdom.” The name arose from the belief that the Zhou Dynasty was at the “center of the world.” Tian Tan, the Temple of Heaven, served to mark the exact center spot. The famous Ricci map puts the “Central Kingdom” clearly at the center of the world. See the map viewer on the University of Minnesota site..
Another important center is the Ka’aba (“The House of God”), a cuboid building in Mecca. It’s the most sacred point within the most sacred mosque (Al-Masjid al-Haram), making it the most sacred location in Islam. Muslims face the Kaaba to pray. For similar reasons, many see Jerusalem as the center of the world.
Some people suggest that a true geographic center can be calculated, but there are many different definitions. One is for a center being a Pole of Inaccessibility, which marks a location that is difficult to access because it is the most distant point from the coastline.
Others suggest that a center of population, is the true center. That would mean that the center lies in Afghanistan.
One could also use the the geographic center of landmass on the earth. But that’s subject to a variety of definitions. Antarctica is a big complicating factor since it’s hard to know what of its coastline to include.