10 U.S.C. § 7779

(a) When the economy of the Army so requires, the Secretary of the Army shall establish military headquarters in places where suitable buildings are owned by the United States. (b) No money appropriated for the support of the Army may be spent for post gardens or Army exchanges. However, this does not prevent Army exchanges from using public buildings or public transportation that, in the opinion of the office or officer designated by the Secretary, are not needed for other purposes.