Close-Up: Azerbaijan's oil baths
This BBC News series focuses on aspects of life in countries and cities around the world. What may seem ordinary and familiar to the people who live there can be surprising to those who do not.
Azerbaijan, on the Caspian Sea, exports millions of barrels of oil to Europe every year. Less well known, is that the thick black oil is also used as a treatment for joint pain.
In the west of the country, a rich variety of crude contains a supposedly curative chemical called Naphthalene.
As the country's wealth grows the town's spa treatment is growing ever more popular.
Tom Esslemont has been to the town to take a look.