Why does the Pantheon have a hole in the roof?

Why does the Pantheon have a hole in the roof?


Discover the Pantheon’s intriguing roof hole, a window for divine observation.



When you first enter the Pantheon in Rome, the first question that might come to mind is: “Why does the Pantheon have a hole in it?”

This opening was supposed to be a kind of window into the building, allowing the divinities to watch over the devoted individuals within. Religious celebrations have been, and continue to be, organized in this historic space despite being so open to the elements. “But, doesn’t that mean it rains inside the Pantheon?”

Sort of. The rain certainly falls through the large hole, but not with the same intensity as it does outside.

The Pantheon in Rome is one of the most significant examples of the architectural genius that was present in ancient Roman civilization. Visiting the building today allows us not only to admire one of the best-preserved historical remains of the city but also gives us the opportunity to reach out and touch the physical embodiment of ancient Roman traditions and knowledge.

Though some might find the large hole slightly bizarre, it is actually the key to understanding the history and beliefs of the Roman people. The Pantheon was built to celebrate all the pagan deities worshiped by the Roman public, particularly the cult of the seven planetary deities: Mercury, Venus, Saturn, Jupiter, Mars, the Moon, and the Sun.

The sun god was undoubtedly one of Rome’s most important deities, a popularity that was established during the reign of Julius Caesar when he initiated a true imperial cult. The role of the “emperor” was transformed into a powerful being influenced by supernatural forces. In short, the emperor became the Sun on Earth.

Thus, it comes as no surprise that a primary role was reserved for the Sun when Marcus Vipsanius Agrippa started building the Pantheon in 27 BC. By allowing the sun’s rays to shine directly into the temple from above, the emperor could enter the building wrapped in its warm light. What better way to celebrate the gods and the link between Heaven and Earth?

The spirituality of the Roman people becomes obvious when we admire the oculus of the Pantheon and imagine the steady gaze of a divinity watching over the faithful followers below.

This ray of light becomes the leading actor on the magical stage set by the Pantheon, which is transformed into a sundial thanks to the oculus.

Numerous calculations were made by the Romans to guarantee that the gods and powers of nature were celebrated with the utmost devotion. The “hole” of the Pantheon was used not only to mark the passage of the seasons but even the hours of the day. Indeed, it is possible to know what time it is simply by observing the position of the sun’s rays inside the Pantheon.

If you are looking for more curiosities and stories about the Pantheon Oculus and the Pantheon Dome, check out our latest article here

Upon seeing the large hole that exposes the building to the external elements, visitors to the Pantheon are often surprised to learn that the temple has regularly hosted religious ceremonies for centuries and is still used today for Holy Mass.

The sun isn’t the only thing that can freely enter the Pantheon. The Oculus is also a convenient entrance for small birds passing through, along with strong gusts of wind, snow, and rain, which could certainly complicate the performance of religious functions.

There is a popular belief that water can’t enter through the hole and that it never rains inside the building. However, it most certainly does rain inside the Pantheon, even if not with the same intensity as outside.

The popularity of this myth comes from what we now call the “chimney effect”, a concept that the ancient Romans were familiar with and used to great effect. The air circulating inside the Pantheon is warmer than the outside, causing it to rise upwards through the hole and somewhat “block” the falling rain, redirecting the drops away from the oculus.

This means that any water entering the Pantheon is always less than what we see outside.

For the rain that does manage to fall into the Pantheon, a system of holes in the floor directly beneath the dome’s opening guarantees that the water is drained away before it can interfere with the regular functions performed inside the Pantheon. This clever system isn’t a modern addition but was actually part of the original structure designed by the ancient Romans themselves, who were absolute geniuses when it came to architecture.