Russian nuclear physicists might have just found one of the oldest churches in the world

Nuclear physicists in Russia may have just detected one of the oldest Christian churches in the world after using muon radiography to scan a subterranean building located in the medieval fortress of Naryn-Kala, in the ancient city of Derbent.

Archaeologists have known about the building for some time and have long suspected it was once used as a Christian temple. However, most of the 40 foot building is hidden underground, with just a dome visible above the surface, and researchers have not been able to access it—excavating could endanger the UNESCO site.

The building is located in the northwest of the fortress and dates to around 300 A.D. It was buried 400 years later when the Arabs captured the city.

There are three main ideas of what its use was—a Zoroastrian fire temple, a reservoir or a Christian citadel. There are several historical references to the building being an underground water tank, however another much larger tank is already known to exist in Naryn-Kaa—making this interpretation problematic.

To find out what the building was used for, researchers from Russian Academy of Sciences, Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State University, and Dagestan State University used a non-invasive technique to create a picture of the buried building. By understanding its structure, they would be able to get a better idea of its former use.

The team placed several detectors inside the building and used nuclear emulsions to create the first images of it. Nuclear emulsion is where photographic plates are used to record the passage of the charged particles that pass through it. Results of the “scan” showed the building was in the shape of a cross—giving weight to the idea it was a church. It was found to be 36 foot high, 50 foot in length (north to south) and 44 foot wide (east to west). The arms of the “cross” were 16 foot wide and 13 foot long.

The team also found an unusual distribution of muons in the western wing of the building, which they say may be architectural features. Findings are published in the journal Applied Sciences.

“It seems very strange to me to interpret this building as a water tank,” study author Natalia Polukhina said in a statement. “In the same fortress of Naryn-Kala, there is an equal underground structure of 10 meters depth, and it really is a tank. This is just a rectangular building. The unusual building, in which we have put our detectors, has the shape of a cross, oriented strictly to the sides of the world, one side is two meters longer than the others.

“As the archaeologists who began excavations say, during construction, the building was entirely on the surface and it stands on the highest point of the Naryn-Kala. What is the sense to put the tank on the surface, and even on the highest mountain? It is strange. Currently, there are more questions than answers.”

Muon detectors are increasingly being used to understand the structures of ancient buildings without having to excavate—and potentially damage the site. In 2017 scientists announced they had discovered a huge chamber inside Ancient Egypt’s Great Pyramid of Giza. “Although there is currently no information about the intended purpose of this void, these findings show how modern particle physics can shed new light on the world’s archaeological heritage,” the team concluded in their Nature paper.