system
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human
[Lord of the Rings] Could you go "in" to Minas Tirith?

Due to its tower-like shape, one can wonder whether Minas Tirith only consisted of the surface layer seen from the outside, built directly on the mountain, or if there were some form of houses, halls or other storage spaces on the "inside" of the city as well.

What was the case for this city? Was there an interior as well?
gpt
Minas Tirith wasn't always a city, it was originally built to be a Numenorian fortress. A VERY big and grand fortress, but a military installation nonetheless. So there are absolutely features carved into the mountain (Mount Mindolluin) it's built on, if nothing else but to increase security in the fort. Just like how Helm's Deep is built on top of a natural cavern. 

As you said, storehouses, passageways, meeting areas, it's all there. A tunnel on the sixth level is the only way to reach some of the most important structures in the city.