The Pentagon
Located in Arlington County , Virginia , across the Potomac River from Washington , D . C . , the building was designed by American architect George Bergstrom and built by contractor John McShain . 
<triplet> Arlington County, Virginia <subj> Potomac River <obj> located in or next to body of water <subj> Washington, D.C. <obj> shares border with <triplet> Washington, D.C. <subj> Arlington County, Virginia <obj> shares border with <subj> Potomac River <obj> located in or next to body of water