Archaeologists stunned after finding secret rooms under a 1,500-year-old Istanbul church

Istanbul, a city famously built on layers of history, has revealed another one of its secrets. Archaeologists conducting excavations at the Saraçhane Archaeology Park were stunned to discover a hidden underground passageway and adjoining rooms beneath the ruins of the 1,500-year-old St. Polyeuctus Church, as reported by Live Science.

The purpose of these mysterious structures is still being pieced together. The subterranean network consists of two large chambers connected by a tunnel, all of which seem to have been linked to the church's prothesis—the chamber next to the altar where bread and wine were prepared for the Byzantine Divine Liturgy.

Researchers were impressed by the craftsmanship; the underground passage is decorated with mosaics, stone inlays, and carved marble blocks.

Screen shot of an underground tunnelCNN TÜRK via YouTube

The Church of St. Polyeuctus has a storied history of its own. It was constructed between 524-527, when Istanbul was known as Constantinople, the capital of the Eastern Roman Empire. According to Anadolu Ajansi, it was commissioned by Princess Anicia Juliana, who "wanted to show power against Emperor Justinianus and his wife Theodora."

The church itself, which was first excavated by archaeologists in the 1960s according to Turkish Archaeological News, is now in ruins. But the discovery of this intact infrastructure is significant, not just for its beauty, but for what it can teach the modern city.

A fenced off area around the church's ruinsDosseman via Wikimedia Commons

Mahir Polat, Deputy Secretary-General of the Istanbul Metropolitan Municipality, told Daily Sabah that the structure's resilience is a marvel.

"Istanbul, which is currently struggling with earthquakes, has experienced dozens of earthquakes over the past 1,500 years. However, the structure we are seeing now has managed to survive all earthquakes. We should learn lessons from this," Polat stated. "The earthquake memory of the city is also here. If you want to see Istanbul's earthquake memory, what happened in the Fatih district is a good example."

Professor Ken Dark, an archaeologist at King's College London who was not part of the project, told Live Science that the ruins are among the city's most significant. "Hopefully, re-displaying the ruins of this historically important and once-magnificent church will bring awareness of it to a much wider audience," he said.

Istanbul, archaeology, St. Polyeuctus Church, secret rooms, Byzantine, tunnels, Live Science, Mahir Polat, Constantinople, earthquake YouTube

This article originally appeared earlier this year.