The center or source of something is known as the locus. A shopping mall is usually a locus for teenagers.
In addition to being a hub or hotspot, locus has specific meanings when used in math or science. In math, a locus is when a set of points all meet at a designated location: a circle is the locus of points equal in length from one given point. In genetics, the locus is the location of a certain gene on a chromosome. A locus is where things are happening. Washington, DC is the locus for politics in the U.S.