CNN - If its ancient walls could talk, Sümela Monastery in eastern Turkey would have quite a few stories to tell.

Since its founding in the 4th-century CE by some of the earliest Christians to arrive along the Black Sea coast, the shrine has witnessed the evolution of the Roman Empire into the Byzantine era, the rise of the Ottomans, the struggle for Turkish independence after World War I, decades of vandalism and neglect, and an almost miraculous resurrection in modern times.

Even more alluring than Sümela’s tumultuous history is a location that seems generated by artificial intelligence or computer graphics rather than a real place — chapels, courtyards, library, living quarters, bell tower, aqueduct and a stone-enclosed sacred spring precariously perched on a rocky ledge nearly 1,000 feet (300 meters) above a wooded river valley in the Pontic Alps.

Every day, thousands of visitors — some of them religious pilgrims but most drawn by the splendor of the early Christian frescoes and architecture that seems to defy gravity — make their way along a cobblestone path to the monastery. Another draw is the fact that Sümela is on UNESCO’s tentative list for designation as a world heritage site.

Now a state museum rather than an active religious community, the monastery has undergone years of meticulous restoration to make the site safe for tourism and mitigate damage inflicted by fires, treasure hunters, vandals and unruly visitors.

“We’ve always had a problem with falling rocks,” says Levent Alniak, manager of museums and historic sites for Trabzon province. “To prevent damage to the structures and harm to visitors, we had industrial mountain-climbers secure the cliff.” Dangling in midair, the climbers used steel cables and huge metal stakes to affix steel mesh netting and barriers to the towering rockface above the monastery.

The ongoing restoration yielded unexpected treasures such as a secret tunnel leading to a previously undiscovered chapel that may have been used as an observation post to defend the monastery. Inside the tiny church, archaeologists found dramatic frescoes depicting heaven and hell, and life and death.

Bringing frescoes back to life

Renewal of the monastery’s exquisite frescoes is ongoing, a multiyear project that involves meticulous, labor-intensive work by art restoration experts. During the summer season when it’s dry enough to undertake the delicate task, visitors can get a close-up look at the restorers removing graffiti and other damage inflicted after the monastery was uninhabited and unprotected between the 1920s and 1960s.

“For many years there wasn’t enough control here and there was a lot of vandalism,” says restorer Senol Aktaş, taking a break from his work on an 18th-century fresco of the Virgin Mary conversing with an angel on the facade of Sümela’s incredible Rock Church. “People wrote their names and other things across the frescos that we are trying to remove by painting over the graffiti with a style and colors similar to what the original artists used.”

As impressive as the exterior frescoes might be, they pale in comparison to the even older images inside. Behind its façade, the church disappears inside a large cave filled with vibrant images created in the 13th century. Large portraits of Jesus and the Virgin Mary stare down from the ceiling, while the walls are reserved for angels, apostles and saints, including a rather graphic depiction of St. Ignatius being torn apart by lions in a Roman arena.

The painted eyes are gouged out on many of the lower frescoes, those within easy reach of human hands. Some have claimed the images were deliberately defaced by Muslims.

But Öznur Doksöz, who’s been guiding visitors to Sümela since the 1980s when it first opened to the public, says there’s another possible explanation. “The Virgin Mary is a holy person for the Muslim people also. So the people who live around here came and scratched their faces, especially the eyes, boiled the paint chips and drank this water thinking it would bless them. We don’t know if this story is true or not, but that’s what people say.”