It’s the Federal Reserve

Diego Garcia was an island exceptionally suited for building military bases. It had a land area of 27 square kilometers and a lagoon covering 125 square kilometers. The lagoon was 10 to 20 meters deep, and the coastline had several excellent harbors capable of berthing multiple large warships. Diego Garcia had a runway 3,660 meters long and 60 meters wide, along with four hangars and two aprons. These formed the main components of the United States' U.S. Air Force base on Diego Garcia.