Plexiglass walkway? I'm thinking more along the lines of transparent aluminum. But you can't have a transparent walkway aboard the ship due to the mechanism under the floor that produces the artificial gravity which cannot be made transparent.
The windows on the left in the tos image may be viewing screens, like on the bridge, which may show the outside of the ship from another angle. Just a guess.
The windows on the left in the tos image may be viewing screens, like on the bridge, which may show the outside of the ship from another angle. Just a guess.
As to the giant viewing windows - I always wondered about them - if they are as tall as they appear you should see a horizontal deck running across them somewhere, especially as how they are toward the underside of the ship. Maybe they are windows into the Enterprise's lower deck giant swimming pool (that's 50 ft. deep!). Crew members could swim while looking out into space!
Reminds me of a resort I went to that had a window in a below-ground bar that looked into the swimming pool!