Article 1, Section 8, Clause 17
Document 20
William Wirt, Right to Tax Government Property
8 Sept. 18231 Ops. Atty. Gen. 620Sir: The constitution of the United States provides that Congress shall have exclusive legislation in all cases whatsoever over all places purchased, by the consent of the legislature of the State in which the same shall be, for the erection of forts, magazines, arsenals, dock-yards, and other needful buildings.
If, therefore, the ground in Philadelphia to which you allude in your letter of the 4th, was purchased with the consent of the legislature of the State of Pennsylvania for either of these purposes, and has been ceded for such purpose, my opinion is, that neither the State of Pennsylvania, nor the corporation, (whose powers are merely derivative from the State,) possess the power to impose and collect taxes from this property.
The Founders' Constitution
Volume 3, Article 1, Section 8, Clause 17, Document 20
http://press-pubs.uchicago.edu/founders/documents/a1_8_17s20.html
The University of Chicago Press