Pentagon road network

The Pentagon road network is a system of highways, mostly freeways, built by the United States federal government in the early 1940s to serve the Pentagon in northern Virginia. The roads, transferred to the Commonwealth of Virginia in 1964, are now state highways. The main part of the network is the "Mixing Bowl" at Interstate 395 (Shirley Highway) and Route 27 (Washington Boulevard), named because it had major weaving issues with traffic "mixing" between the two roads before it was rebuilt in the early 1970s.

The nickname is now more commonly used to refer to the Springfield Interchange, where I-395, I-495, and I-95 converge in nearby Springfield.

The Henry G. Shirley Memorial Highway was built to take traffic off the Highway Bridge (now the 14th Street Bridge). The first phase, from the bridge to Arlington Ridge Road, was completed in 1942. This began at an existing cloverleaf interchange with the Mount Vernon Memorial Highway and ran southwest, parallel to the existing Jefferson Davis Highway (U.S. Route 1), to a point southeast of the Pentagon. That section included an interchange with Boundary Channel Drive, which served the Pentagon's north parking lot, and a bridge over the Rosslyn Connecting Railroad. US 1 was routed onto it, as the existing US 1 was cut in several places by ramps.