Which structure currently operates as a "virtual fence:"  Boarder Wall or Mexico-United States Barrier?
Mexico–United States barrier The Mexico–United States barrier is a series of walls and fences along the Mexico–United States border aimed at preventing illegal crossings from Mexico into the United States. The barrier is not one continuous structure, but a grouping of relatively short physical walls, secured in between with a "virtual fence" which includes a system of sensors and cameras monitored by the United States Border Patrol. As of January 2009, U.S. Customs and Border Protection reported that it had more than 580 mi of barriers in place. The total length of the continental border is 1,989 mi .
Manchester Wall Manchester Wall, located in downtown Richmond, Virginia, U.S., is one of central Virginia's premier rock climbing areas, offering multiple routes for trad climbing, sport climbing, and top roping. The sixty-foot granite wall is a remnant of the Richmond and Petersburg Railroad Bridge which spanned the James River for much of the nineteenth century. The climbing area is located on the south side of the James River and is accessible by foot from the north via Brown's Island and the T. Tyler Potterfield Memorial bridge, also known as the Brown's Island Dam Walk. There are also two parking lots that allow walk-up access from the south; one on W 7th Street and Semmes Avenue, and the Floodwall parking lot located at the south end of the Mayo Bridge. The routes offered at Manchester Wall, and its 3 adjacent pillars, are superb for recreational and experienced climbers alike.