Construction of Pantheon

The Roman Pantheon is a temple dedicated to all the gods. It is a well-preserved monument of the ancient Rome and thus, holds a significant importance in the architectural history. Pantheon was built by the Roman Emperor Hadrian between AD 120 and 124 from the original temple built in 25 BC by Agrippa, son-in-law to Augustus. The temple was converted into a church in the 7th century AD and is known as S. Maria Rotonda.
Portico is the porch attached to the building where the roof is supported by columns at regular intervals. This was the original temple built by Agrippa. The columns are made of granite and the Corinthian Columns rest on top. The rotunda is the main room with the dome built by Hadrian. This was the first round temple for its scale. The rotunda is consisted of eight recesses. One was the entrance and the rest provide shelter for the statues of the seven major Roman gods. The height of the stepped dome and the diameter of the drum are 147 Roman feet. Oculus is a round opening in the dome. It is 30 feet wide and used as a source of light to the interior. It also reduces the massive weight if the whole structure. The dome was covered by gilt bronze until 655, but it was later replaced by lead. The walls of the Pantheon were 21 feet thick and were made up of concrete. They were in between the layers of brick facings and the marble veneer. The dome was made with a thinner layer as it reaches the center, to reduce massive weight of the dome. The columns and walls were set in a technical way to bear weight of the structure.
The Pantheon or the S. Maria Rotonda is a unique surviving monument of the Ancient Rome. It was built with several techniques of reducing weight, and adding decor to the structure.