Pamukkale, and the Romans who came for the water

From a distance, Pamukkale looks improbable even by the standards of Turkey's landscape: a hillside apparently covered in snow, in a region that rarely sees any. Closer up, the white is travertine, a form of limestone deposited by mineral-rich hot springs that have been running down this slope for hundreds of thousands of years, cooling as they go and leaving calcium carbonate behind in terraces, ridges and shallow pools that step down the hillside like a formation nobody quite designed.

Water that built its own landscape

The name Pamukkale means "cotton castle" in Turkish, a fair description of the terraces' texture and colour, and the process behind them is straightforward chemistry given an enormous amount of time: the spring water is saturated with calcium bicarbonate, which becomes unstable as it reaches the air and cools, precipitating out as solid calcium carbonate. Repeated over millennia, that slow mineral deposit has built up a hillside that looks sculpted rather than grown, and the pools that collect in its folds have been used for bathing since antiquity.

A spa city built on top of it

Recognising a good thing, the kings of Pergamon founded a city, Hierapolis, at the top of the terraces in the second century BC, and it flourished under Roman rule as a spa town, drawing visitors who believed, not unreasonably, that mineral-rich hot water was good for what ailed them. The remains are extensive: a well-preserved theatre built into the hillside, colonnaded streets, monumental gates, and one of the largest necropolises anywhere in Asia Minor, its tombs stretching for well over a mile along the old road into the city, evidence of just how many people chose to be buried near waters they had once come to for their health.

Like much of western Turkey, Hierapolis suffered repeated earthquake damage over the centuries, and the ruins visible today are, in places, the result of Roman and later Byzantine rebuilding after tremors that had flattened earlier versions of the same buildings. A large bathhouse complex near the theatre was eventually converted into a basilica once Christianity became the dominant faith of the late Roman world, a change of use that turned up again and again across the empire as old civic buildings found new religious purposes.

A pool with a legend attached

Within the ruins, a thermal pool now known as Cleopatra's Pool is said, by local tradition rather than firm historical record, to have been a gift from Mark Antony to Cleopatra, and it is scattered with fallen marble columns, toppled by an ancient earthquake, that bathers swim among rather than around. Whatever the truth of the story, the pool's water is measurably warm, and the combination of ancient stone and mineral spring has made it one of the more unusual bathing spots anywhere on the Turkish coast circuit.

The gate the Romans took seriously

Hierapolis holds a stranger site too: a small cave known in antiquity as the Plutonium, dedicated to Pluto, god of the underworld, and described by ancient writers including the geographer Strabo as lethal to anyone who entered it, with birds reportedly dropping dead if they flew too close. Modern investigation has confirmed the explanation: the cave vents naturally occurring carbon dioxide at concentrations high enough to be fatal at ground level, a genuinely dangerous geological feature that the Romans, without the chemistry to explain it, understandably took as proof of a passage to the underworld.

Geology doing the persuading

The springs that feed Pamukkale are not evenly distributed, and the terraces closest to the modern entrance have, over the decades, seen enough foot traffic that access to some of them is now managed carefully to let the mineral deposits keep forming. Visiting earlier in the day, before the terraces are at their busiest, tends to make more of a difference here than at most ancient sites, since both the light on the white travertine and the ease of finding a clear pool improve considerably before the height of the day.

Pamukkale and Hierapolis make an unusually persuasive pairing precisely because neither one needs much embellishment. The terraces are a genuine, slow-motion geological process, still active today, and the ruined city above them grew directly out of what that process produced. Few ancient sites make quite so literal a case for why people built where they did.