What river is the location of the PENREN across from?
Pentagon Renovation Program: The Pentagon Renovation Program or PENREN was a long-term project by the United States Department of Defense to perform a complete slab-to-slab renovation of The Pentagon in Arlington, Virginia. The Pentagon: The Pentagon is the headquarters of the United States Department of Defense, located in Arlington County, Virginia, across the Potomac River from Washington, D.C. As a symbol of the U.S. military, "The Pentagon" is often used metonymically to refer to the U.S. Department of Defense.
the Potomac River