The invention is a system, apparatus, and method for treating or repairing, an aneurysm in a large vessel, such as a thoracic aneurysm. The systems, devices, and methods of the present invention include a first prosthesis for anchoring a proximal end of the system in the blood vessel, a second prosthesis for anchoring a distal end of the system, and at least one third second prosthesis for bypassing the aneurysm, the first prosthesis optionally further comprising a seat or the like adapted and configured to receive the third prosthesis.