Niskanen Center — Headquarters: 1201 New York Ave NW, Suite 200B, Washington, DC 20005

NoteThe source text is from the official Niskanen Center contact page and explicitly lists the organization's headquarters address under the 'Where To Find Us' section. The address matches the claim exactly: 1201 New York Ave NW, Suite 200B, Washington, DC 20005 (with minor formatting variation: 'D.C.' vs 'DC', which is not a substantive difference).