Made a nether portal went thru it and did /rt . I found a city and I could not mine or place any blocks.
that's normal, it's so the cities don't get destroyed / need to be reset so often, you can break book shelves, Smelteries, High oven, Marble and Pneumatic craft stuff as well as Redstone energy cells. everything else is untouchable (to my knowledge) except that you can open chests, and that all of those blocks I just mentioned get regenerated after an hour or so (I think.)
Yes it is normal. Only certain blocks are white listed. There was also some glass I was also able to break near a high oven controller.
