In roman basilicas columns and pillars are
arranged in an alternating sequence to break up the
rigid impression of the unpretentious architecture.
Usually the large arcs of the central nave are carried
by pillars. These arcs are divided into smaller
arcs (given by the size of the aisles) which lie
on columns. If the size of the aisles arcs is half
of the central nave then pillars and columns
alternate strictly. If the ration is one to three,
each pillar of the central nave is followed by
two columns of the aisles that are usually thinner.
This kind of secquence can be seen in St. Michael
in Hildesheim (see left image).
Originally "Hall of the King" (probably after the hall of
the archon Basileus in Athens), building with a large
cetral nave with one or more suplemental, smaller
aisles at each of the long sides. The romans used
this kind of buildings primary as multi-purpose
halls (as market building and courtroom),
than the christs took this concept as basis for
the romanic churches. The central nave is higher
than the side aisles so in the upper part there
are usually windows to let some light into the
church. The use of romanic arcs (that can only
form quadratic vaults) leads to the ad
quadratum construction of basilicas:
the width of the central naves bays is a mutliple
of the side aisles (usually two or three times)
so that all other units of the building can be
derived from the units of the crossing.
In later centuries the basilica is extended by
the choire, towers and the westwork. In the late
middle age the basilica is replaced by the
hall church.
In mediaeval paintings and books the four evangelists
are often represented by their symbols.
Here are the symbols, the according evangelists and
an example image:
A dividing wall between the central nave in which the
community watched the service and the choir
that was reserved for the clerics. Rood screens
were common since the 13th century. The rod screen
usually had one or more openings but limited the
sight into the choir. Rood screens did not fit into
the new liturgy (mainly because of the reformation)
because they stood between the community and the
Sacrifice of the Mass. For this reason most rood screens
were destroyed in the late middle age.
In Carolingian times an extension of the church was
build on the western side, opposite of the choir.
This extension is called westwork and usually
contained the baptismal font. The upper floor
offerd room for the emperors and their
retinue. So the growing size of the westwork
during the following centuries is a sign of the
growing power and influence of the secular
rulers. Since the high middle ages even the towers
of the church are usually located in this western
part.