I have not played there; I know there has been at least one redesign, but I have no idea how much of the original Ross remains.
Bacon Park in Savannah has 16 Ross holes that are essentially untouched; the other two were changed because of highway construction. The problem is that an additional 9 holes were added much later and the Ross holes are split up among the three nines. The Savannah Open each year plays over the Ross holes and then the course stays that way for a couple of weeks for the general public. They have scorecards of the original course, and with some work to figure out where you are you can pretty easily play the original course.
Bacon Park is very public, and not in the greatest condition. But it is distinct Donald Ross and a lot of fun, especially if you like public golf in the first place.