Stone Pier                                             -      -     NE 
(-------------------------------------------------)     - <---(M)---> -
                                                        -      S     SE

The church is defined by the eight large stone piers that alternate with
the curved, columned niches, pushing outward.  These vertical supports soar
all the way up the to the top of the church, some fifty feet above ground. 
The complex piers, their nuclei almost concealed by attached pilasters and
engaged columns, called 'cluster piers' which support the heavy dome in the
center.  To your south you can see a small recess in the wall, a niche, and
the surrounding forechoir to your northeast and southeast.  Between the two
large piers is a narrow marble staircase leading to the ambulatory located
on the second floor.  
A diocletian choir member praises with open mouth.
A diocletian choir member praises with open mouth.