Route 27 is near the site of the September 11 attacks on the Pentagon. Many commuters and drivers on the road witnessed the hijacked American Airlines Flight 77 fly directly over Route 27 and crash into the Pentagon. Witnesses included Daryl Donley and Steve Riskus, both of whom took some of the first photographs after the plane crashed. As the plane passed over Route 27, it clipped several light poles; one light pole landed on the windshield of a taxicab driven by Lloyd England. The section northeast of I-395 was closed for several weeks following the attack as a security measure. When it reopened, "No stopping" signs were placed along the section of Route 27 near the Pentagon. To increase security, the cloverleaf interchange between Route 27 and Columbia Pike was reconfigured, by eliminating the separate loop ramp from eastbound Route 27 to westbound Columbia Pike. The ramp from westbound Columbia Pike to eastbound Route 27 was relocated parallel to Route 27 and the resulting freed area was used to construct a security checkpoint leading to a new Pentagon loading dock. A driveway from the checkpoint runs parallel to Route 27 separated by a high metal fence. However, the Pentagon Memorial still remains visible behind this fence. North of the memorial, a high cement retaining wall and berm has been constructed to protect the Pentagon from any possible explosion threats on Route 27. These and related security improvements cost $35 million (equivalent to $ in ) and were completed in October 2004. On September 11, 2010, the portion of Route 27 near the crash site was dedicated as "9/11 Heroes Memorial Highway" after receiving that designation by the State Legislature. Commemorative signs have been added on both sides of the highway.