Turkey's "Cotton Castle" Is A Mineral Forest For A Natural Spa

Calcite has transformed the landscape of Pamukkale in Turkey where the “Cotton Palace” has sprouted a mineral forest.


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

travertine pools at Pamukkale

The petrified waterfalls and terraced basins look like a dreamy cascade of infinity spas, which is exactly what they once were for the kings of Pergamon. Image credit: Ryzhkov Oleksandr/

This article first appeared in Issue 7 of our free digital magazine CURIOUS. 

Since the second century BCE, the city of Pamukkale, which neighbors the ancient Roman site of Hierapolis, has been used as a natural spa. The ancient formation was once believed to have healing powers, decked out with hot thermal springs and white terraces that make for some pretty visually stunning R&R.


The natural site in Denizli Province in southwestern Turkey was made possible by thermal spring water that brought bucketloads of calcite into the region. It’s classed as travertine, a type of limestone that forms when a mineral-rich lake or river system evaporates and leaves behind a crusty, but admittedly quite beautiful, calcium carbonate trail.

As a UNESCO World Heritage Site since 1988, it’s recognized as a site of cultural and natural heritage to be protected and admired. A fitting status for a spot that once bathed the kings of Pergamon, a Greek state that ruled during the Hellenistic period.

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Hierapolis is the name of the ancient Greek city that was built on top of the travertine formation, which has been nicknamed the Cotton Palace for its snow-white limestone. The crusty cotton formed over millennia as mineral-rich waters dripped down the mountainside.

As a type of sedimentary rock, the travertine was deposited by 17 hot springs in the region whose temperatures range from 35°C (95°F) to 100°C (212°F), aka balmy to boiling. The milder temperatures made for a warming spa for humans of the second century BCE at a time when doctors considered it to be a healing center.


The site’s historic significance is remembered in a museum that contains historical artifacts including Bronze Age trinkets. Its past is also spelled out in archaeology, as the site boasts the Theatre of Hierapolis and a necropolis (ancient cemetery) with sarcophagi that stretch for over a mile. 

How to get there

The Çardak Airport is the nearest airport to Pamukkale. From there, it’s around an hour’s drive.

CURIOUS magazine is a digital magazine from IFLScience featuring interviews, experts, deep dives, fun facts, news, book excerpts, and much more. Issue 10 is out now.


  • tag
  • geology,

  • minerals,

  • World Heritage Sites,

  • hot springs,

  • calcite,

  • sedimentary rocks