The prehistoric monument caught everyone's eyes, a piece of the past to not be forgotten.
I think it was named the bald eagle because of the contrast in colors. The body is brown and the head is white, like you said, so when it is flying it looks bald because the head is lighter. I think that might be the reason
I would say warriors as common noun refers to a concept to a particular individual .
It is dark because Barnardo has trouble seeing the other guard.
This scene takes place at midnight and it is so dark Barnardo cannot see the other guard. Barnardo shows up for his shift, but he can't clearly make out who Francisco is. Francisco has the same problem because instead of answering Barnardo he tells him to identify himself first. They get it figured out and Barnardo begins his shift.