They have. It's a few levels higher. The robbers tunnel is easier to reach from the ground, so it became the main entrance for visitors for centuries now.
Is the main entrance actually opened/digged through? (I know it's not really needed, just curious).
It is not very clear from the picture outside. You can have a glance of the other side (as part of Descending Passage) as well in OP's tour, but again not clear, the view is blocked by something there.
