Pantheon of Rome: Architecture, History and Construction

Formal Description

Chronology: The original structure dates to 27 BC, with a major reconstruction occurring between 118–128 AD under the reign of Emperor Hadrian. Located in Rome, near the Campus Martius, it stands as a masterpiece of Roman Imperial architecture, utilizing both trabeated and vaulted construction systems.

The original temple differed significantly from the current structure; the entrance was positioned on the opposite side, and the cella was transversal. The current church features a facade oriented to the north. During the reconstruction, the temple was expanded, incorporating an existing square and adding an arcaded plaza before the main entrance.

The Pronaos (Portico)

The portico is octastyle and rectangular, utilizing a trabeated construction system. The Corinthian columns support an entablature featuring the bronze inscription: M. AGRIPPA L. F. COS. TERTIUM FECIT, which translates to "Marcus Agrippa, son of Lucius, consul for the third time, built this."

• Pediment: The entablature is crowned by a triangular pediment, currently undecorated.
• Interior Layout: The porch contains two rows of four columns, dividing the space into three aisles. The central aisle is wider, providing access to the naos via two large bronze doors.
• Side Niches: Flanking the entrance were niches housing statues of Agrippa and Augustus.
• The Drum: The portico connects to the naos via a cylindrical wall known as the drum, which supports the dome and provides elevation. It was constructed using opus caementicium (mortar) and opus latericium (concrete).

The Naos

The interior features a series of recessed coffers. The five rows of coffers represent the ancient planetary system, with each row corresponding to the 28 days of the lunar month. These coffers serve both decorative purposes and to lighten the weight of the dome.

• The Oculus: A 9-meter diameter opening at the apex provides light and ventilation.
• Flooring: The floor is composed of colored marble arranged in geometric circular patterns.

Historical Background

The Pantheon was constructed during the Pax Romana, a period of relative peace and stability. Following the Battle of Actium (31 BC), where Emperor Augustus secured victory, his general Agrippa—a skilled military leader and architect—commissioned the original Pantheon, along with aqueducts, baths, and gardens.

After the original structure was damaged by fire, Emperor Hadrian (who ruled from 118 to 138 AD) ordered its reconstruction. Hadrian, born in Hispania, was known for:

• Extensive travels to address administrative and economic reforms.
• A robust policy of public works and infrastructure development.