I had no idea how huge & involved that project just in Oak Ridge was until we watched the documentary on PBS. A whole city was created very quickly to accommodate the personnel that supported that project.
I live about 15 miles east of it. Yeah the reservation for the DOD/DOE plants is still large and several facilities are still in operation.
During WW2 to enter the city unless you were an employee you someone had to sign you in at one of about four gates in and out of town. The gates still stand actually or rather the fortified building the guards were in do. My aunt and uncle lived in Oak Ridge during the project. When my Mom went to visit her sister my uncle had to meet her at the gate to sign her into town. Now the city has also become somewhat of a sanctuary city for illegals.