Castles and Fortifications in Middle-earth

[Kent2010]

Speaking of central towers, the Tower of Ecthelion in Minas Tirith, seems to be the stand out feature. We get two descriptions of the Tower - first through Pippin's eyes when he first sees the city, and again when the entire city is being described.

I wonder about the position of the Gates. The first gate looked East, but rest of the gates weren't in line, they wound back and forth to the topmost level:

But the gates were not set lin line: the Great Gate in the City Wall was at the east point of the circuit, but the next faced half south, and the third half north, and so to and fro upwards; so that the paved way that climbed towards the Citadel turned first this way and then that across the face of the hill.
-Minas Tirith

Has this staggering of gates back and forth, been used in any type of castle before?

Edoras seems to be similar to the hill forts in England and Wales. Basically, on top of a hill sat the hall, monastery, chapel, what have you and it was encircled by a wall - sometimes two walls. Some weren't just military fortifications but were towns and places for business.

'I see a white stream that comes down from the snows,' he said. 'Where it issues from the shadow of the vale a green hill rises upon the east. A dike and mighty wall and thorny fence encircle it. Within there rise the roofs of houses; and in the midst, set upon a green terrace, there stands aloft a great hall of Men...'
-King of the Golden Hall

Edoras is a place for both. You have people living within the walls, but also the King who has his guard and other soldiers.