Archaeologists in southwestern Turkey have uncovered an astonishing architectural transformation in the ancient city of Kaunos—one that spans more than a millennium of history. Excavations near the city’s harbor have unearthed a Roman hospital that was later converted into a Byzantine monastery complex with a remarkably well-preserved church, offering an extraordinary window into the city’s evolution from a healing center to one of religious devotion.

Kaunos Ruins. Haluk Comertel; CC BY 3.0

Kaunos, located in Muğla’s Köyceğiz district and listed on UNESCO’s World Heritage Tentative List, is already famous for its rock-cut tombs, a 5,000-seat theater, baths, and mosaics that are over two thousand years old. The recent discoveries, however, indicate another side of the ancient city’s history—its centuries-long life as a hub of medicine, religion, and cultural continuity.

Led by ᴀssociate Professor Ufuk Çörtük of Muğla Sıtkı Koçman University, excavations have focused on the so-called “Archaic walled monastery area.” Over the past three years, his team has uncovered layers of structures and artifacts that bear witness to the site’s evolving functions over the centuries. The earliest ruins are those of a Roman complex dating from the second and third centuries CE, which has been identified as a hospital or health center due to the vast quanтιтy of medical instruments unearthed.

The structure featured a courtyard with rooms surrounding it, similar to other Roman hospitals known to have originated as military facilities before civilians used them. As it was near Kaunos’ ancient harbor, it would have treated residents and travelers amid the port city’s bustle.

Roman baths of Kaunos. Credit: AlexanderVanLoon; CC BY-SA 4.0

By the sixth century CE, this formerly medical complex was transformed drastically. Archaeologists unearthed a large Christian church built directly atop the earlier Roman foundations—an indicator that the site had become part of a walled monastic complex during the Byzantine period. The well-preserved church reflects the city’s transformation into a spiritual center while preserving its architectural continuity over the centuries.

The excavations also produced evidence of later occupation. A coin of Aydın Mehmed Bey of the Aydınoğulları Beylik, a Turkish principality from the 14th century, demonstrates that the site remained in use far into the medieval period. Çörtük noted that Kaunos experienced at least four or five distinct phases of use between the second century CE and the Turkish-Islamic period.

Rock-cut temple tombs in Kaunos. Credit: Alim Dağ

Researchers call the site a “living timeline” of Kaunos’ continuous adaptation through changing empires, beliefs, and social needs. It evolved from a healing sanctuary in the Roman world to a sacred Christian complex before becoming part of the Turkish Anatolian fabric.

The discovery underscores the ways in which Kaunos—among ancient Caria’s most significant port cities—embodied the intersection of medicine, religion, and daily life in the eastern Mediterranean.