D.C. Code § 44-711
All sums of money appropriated and expended in aid of the purchase of real estate for charitable or reformatory institutions in the District of Columbia, or for buildings or for permanent improvements to buildings thereon, shall (subject to any trust deed, mortgage, or other security or encumbrance existing on such property at the time of its purchase, or created at the time of its purchase) be a lien upon such property, and in case of the dissolution of any such corporation owning such property, or in case of the disposal of such property, by such corporation, entitle the United States to reimbursement in proportion to any other contributions or funds used for such purposes; and the acceptance by any such corporation of any sum of money appropriated for the foregoing purposes shall be deemed an acceptance of and agreement to this provision.
D.C. Code § 44-711
Public land sales, see § 10-801 et seq. .