Architecture of the Pantheon

Something similar can be seen in the small temple of Portunus at the Forum Boarium or even better in the remains of the temple to the Divine Hadrian at Piazza di Pietra. Access to Agrippa’s original Pantheon was from the opposite end.

A fire caused it to be rebuilt in 80AD by Emperor Domitian and lightning meant a further reconstruction by Hadrian around 123AD who changed it quite radically by introducing the Rotonda and at best used the foundations of Agrippa’s original. Access to the temple was afforded by climbing a set of steps up to the portico of wonderful monolithic columns we still see holding up the triangular pediment. Three columns at the back left are actually replacements taken a few centuries ago from Nero’s baths nearby.

Passing through the columns leads to the large bronze doors and into the temple itself. The whole building was framed by a pedestrian square with statues and portico of columns. The temple was set on a pedestal above road level, which at the time was below current road level. You can gain an idea of how road level has changed by taking a walk round the back to be confronted by a deep moat.

The building’s exterior was veneered in polished white marble and the dome was covered in bronze bricks plated with gold. The portico was protected by 200 tons of bronze slabs which were pinched in the C17th by Pope Urban Viii Barberini to make 80 cannons and for the sculptor Bernini to build the baldachin over the altar at St. Peter’s.

The interior, called the “Rotonda”, is round and is accessed through a pair of extremely imposing bronze doors. It is often said that they are still the Roman originals but there are rumours that they are possibly Renaissance remakes.

The horizontal and vertical diameter of the interior space is of 43.2 meters: the main body of the building is conceived and built around a sphere of that dimension. It should be remembered that to the Romans the sphere represented not only perfection but also the heavens. This sense of geometric perfection permeates the entire structure.

The walls are three storeys high and up to 6.2 meters thick with weight distributing arches built in to the brickwork in order to achieve the greater height and strength required to support the dome. The wall thickness was necessary to act as a buttress against the domes’ enormous stress.

On the inside, the perimeter wall opens up into a series of niches which once contained statues which given the building’s name “Pantheon” were probably of several deities. It is likely that the statues were of the planetary gods given that at the time there were 7 known planets if we include the sun and moon. This fits quite neatly with there being 7 niches to house them in. The niche facing the entrance doors is the most important both in dimensions and decoration. Perhaps it housed Jupiter Optimus Maximus.

Experiencing the Pantheon’s architecture

Entering the Rotonda we immediately get a sense of monumental simplicity and perfection. Throughout the whole building we can witness the repeated use of the geometric forms and proportions used for the building’s overall conception. For example triangular pediments, the semicircular dome over the central niche, Corinthian columns and so on. The floors are a beautiful example of opus sectile roman mosaics utilise the same materials, colours and pattern shapes as are utilised in the rest of the building’s decoration. They not only reinforce the building’s shape but the modular approach enhances the individual’s point of reference of himself versus the size of the building as a whole. We can imagine how a plebeian would have been impacted by the sense of space, the view of the emperor standing on a podium, surrounded by statues of the divinities and lit by the light of the heavens. A similar approach to the flooring can be seen in the paving of Trajan’s forum.

Through the ages the different statues which stood in the niches have been replaced by Christian altars and sepulchres such as those of the kings of Italy. The most visited burial is perhaps that of the renaissance painter Raphael. In accordance with Raphael’s will, his mortal remains are held in a sarcophagus of classical style looked upon by a painting entitled the “Madonna of the stone” (Madonna del sasso) painted by one of his pupils, Lorenzetto.

Read on to part 3 – about the Dome and Construction techniques of the Pantheon
Architecture of the Pantheon part 1 – General Introduction
Architecture of the Pantheon part 2 – Description of the Pantheon
Architecture of the Pantheon part 3 – The Dome and Construction Techniques