Final answer:
The location of the new DC headquarters and practice stadium has not been publicly announced. Washington D.C. is the capital established by Congress, where federal entities, including sports facilities, might be developed.
Step-by-step explanation:
The question asks about the location of the new DC headquarters and practice stadium. The national government of the United States is based in Washington D.C., which was selected by Congress under Section 8 Clause 17, granting it the power to establish a capital outside the jurisdiction of any state. This area was originally part of Maryland and Virginia and is along the Potomac River.
As of the information available, there has not been a public announcement regarding the specific location of the new DC headquarters and practice stadium. Such facilities typically involve significant planning and negotiation, especially when they are associated with a major sports team or a federal entity in Washington D.C.