Wydaje mi sie, ze chodzi o trzon, wokol ktorego powstaje galeria. Por. z innej wprawdzie branzy:

In addition to the vital research they provide, colleges and universities are anchor institutions that offer their communities a job base, demand for local goods and services, and capital and technical assistance to support revitalization. A number of higher education institutions in the Northeast are already providing substantial resources to revive the neighborhoods, school systems, and local economies of their home towns. Being an "anchor" means that the institution is there to stay, that it will not be leaving, as so many industrial firms left in the past three decades, to follow lower labor costs or other business advantages.
http://www.hud.gov/library/bookshelf18/pressrel/nowtime.html