I went on a tour of the ORNL complex, and although there are modern research facilities there, the Manhattan Project buildings are pretty much still there.
Some of these places are pretty decrepit, dodgy, near derelict in condition, some are being demolished (K-25 gas diffusion plant for one) . I have some pics, as photography is restricted in most places.you should be able to find additional pics on the net.
The Graphite reactor is the best of the stops, this is the original reactor, not that there is alot to it, a pile of graphite blocks surrounded by concrete mostly.they only let you see the loading face, and the control room. Then they take you to the lookouts surrounding the K area, though at a distance, you can get some pics of the buildings where Uranium was enriched for the A bomb.
More pics…keep the interesting pics coming.