I just posted the message on the possible location of Camp Holmes and spent some time on the Library of Congress map and Google Earth. On the 1872 map there is a major railroad complex just north of where McDowell St and Dawson come together.
I was looking comparing Google earth to the 1872 map of Raleigh. In the 1872 map there is a round house in the railroad complex. In approximately the same location on Google Earth is a railroad turn table where Trains would be turned to enter a round house of another track. Is this part of the complex shown on the 1872 map.