It says "We're entering today through a Robber's Tunnel, a tunnel that some believe was created in 820 AD by Caliph al-Ma'mun, when he was trying to break into the pyramid."
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.
