D.C. Code § 47-1012

The buildings and grounds of the Louise Home, and all property held by the trustees thereof for the purposes of the trust contained in a certain deed from William W. Corcoran dated November 21, 1869, and recorded in liber 630 at folio 458 of the land records of the District of Columbia, on the square no. 166 shall be free from all taxes and assessment by the municipal authorities, or by the United States, so long as the same shall be held and used for the purposes of the said trust.