upolas, the latter by barrel-vaults. Only the niche
opposite the entrance is, at the present time, uninterrupted, and
open up to its full height, thus corresponding with the formation of
the entrance section; in front of each of the others, two columns have
been erected, the beams of which close the opening of the semicircular
vault. To this chief portion of the building is attached the splendid
portico which, in the manner of the above-mentioned temples, projects
by three columns, besides a massive wall-structure. The frontage
shows eight columns. As a rule, the whole space of the pronaos was
without columns; contrary to the rule we here see it divided into
three naves by means of two pairs of columns. The center nave, which
was also the widest, led to the entrance-door, each of the two others
being terminated by an enormous niche. Not to mention aesthetical
considerations, these columns were required as props of the roof
covering the vast space (the portico is about 100 feet long).

[Illustration: INSIDE VIEW OF PANTHEON.]

The columns of the portico carried beams, on the frieze of which the
following inscription in large letters has been placed:
M.AGRIPPA.L.F.COS.TERTIUM.FECIT. Another inscription below this one,
in smaller characters, states the building to have been restored by
Septimius Severus and Caracalla. The beams carry a large pediment,
originally adorned with groups of statues representing Jupiter's
victories over the Gigantes. Behind and above this gable rises a
second one of the same proportions, serving as an ornament of the
projecting wall which connects the round building with the portico.
The roof of the portico was supported by beams made of brass.
According to the drawing of Serlio, these beams were not massive, but
consisted of brass plates riveted together into square pipes--a
principle frequently applied by modern engineers on a larger scale in
building bridges, etc. Unfortunately, the material of the roof,
barring some of the large rivets, has been used by Pope Urban VIII.
for guns and various ornaments of doubtful taste in St. Peter's
Cathedral. The large columns carrying the ugly tabernacle on the grave
of St. Peter are one of the results of this barbarous spoliation. The
old door, also made of brass, which leads from the portico into the
interior has, on the contrary, been preserved. The outer appearance of
the round building is simple and dignified. It most likely was
originally covere