Under a Barrel-Vaulted Bay                             -      -      - 
(-------------------------------------------------)     W <---(M)---> E
                                                        -      -      -

Looking up you see one of the six great decorative features of the
basilica, the large vaulted bay.  It is part of the alternate-support system
that holds the structure together.  This design feature allows the high
ceiling found in the main hallway, which with the help of clerstory windows,
demonstrates the skill of the architects.  Flanking the east and west are
two long corridors.