At Wednesday's chat, the question came up: "How far apart are the seven hills? Would villages of 150 people spill over into each other?" I thought and do think they wouldn't (someone also made the argument that a hut might contain five or more people):
Here is a Wikipedia article (as usual handle with care) on the seven hills, with this map from Wikimedia commons (click to enlarge):
Here is another one: The Seven Hills of Rome. (from Roman History & Mythology)
Neither map gives distances, but the second one describes walls surrounding some of them. And this one does give distances. (main site)
And finally, this article by N.S. Gill has photos that give an indication of the size of the hills – with the provise of the erosion as described in the link above.
If someone finds a better map, please let me know or leave a comment below.