Atrium:
The door back to the courtyard goes to the back halls of the first floor.
The main cathedral doors go to the second basement (what you all called the kennel).
The first side door goes to the mezzanine of the grand hall.
The second side door goes back to this very room.
The mezzanine door goes to the up fork of the tower, which is where you just were.

Mirror room
The first side door to the lower tower (where the stairs are impossibly long).
The second goes to another chamber off the kennel basement (another monster chamber).
The third one goes to another slave cell, a different one from before.
The ceiling one goes to a chamber with a sacrificial altar.
The one you came through goes back to the atrium.

Kennel
?? door leads to mirror room.

Mezzanine
door from atrium @top => back halls of the first floor
other top mezzanine door => down fork of the tower
@bottom The right one leads to the a chamber off the second basement
@bottom left one leads to the lower tower (before the fork)

Lower tower before the fork
door from Mezzanine => atrium
1 st door => kennel
2 nd door => hellmouth

hellmouth
entrance => priest’s room

priest’s room => slave’s cell

slave’s cell => mirror room