For many of the seven million tourists who come to Istanbul every year, a trip to a hamam, or traditional Turkish bath, is a highlight of their visit - an authentic Ottoman-era experience.
Dressed only in a skimpy cotton wrap and noisy wooden sandals, you sit in a drippingly humid steam room, under a perforated stone dome from which shafts of light stream down.
You are then led by beefy tellaks, traditional masseurs, to a heated marble slab in the middle of the chamber, and vigorously scrubbed and slapped around, before dousing yourself in cool water from the old brass taps set in the walls..
Perhaps borrowing some ideas from the bathing habits of the city's original Roman inhabitants, the Ottoman conquerors of Istanbul built some 150 hamams there between the 16th and 18th Centuries, and many more in other cities.
Some of the finest were built by Sinan, the most renowned architect of the Ottoman era.
For wealthy women of the period a trip to the hamam was part of the daily routine; they would spend hours there relaxing, chatting, and being groomed by their servants.
But over the past century the habit has died, and most of the original Ottoman hamams have fallen into disuse: some demolished, others converted into bars or store rooms.
Of the 48 hamams believed to have been built by Sinan, just a handful survive,, some of them in ruins.
There is a lot more interest in preserving our historical heritage now, and it is not restricted to more spectacular buildings like mosques. Hamams, and even Ottoman-era factories, are being renovated
Historian Nina Ergin
Only a few, like those in tourist areas - such as Cemberlitas, near the Spice Bazaar, and Cagaloglu, a stone's throw from Hagia Sofia and the Blue Mosque - have continued to thrive.
Cemberlitas was built by Sinan in 1584, as a commission from the wife of the Sultan. Cagaloglu was built in a spectacular neo-baroque style in 1741. A water crisis later in the 18th Century forced the Sultan to ban all further hamam construction.
"Most hamams were built to help fund the big foundations that were a feature of the Ottoma era," says historian Nina Ergin.
"They were rented out to fund mosques, hospitals and soup kitchens. But at the end of the 19th Century many of those foundations ran into financial difficulties, and offered rental periods of 200 to 300 years. That's how so many hamams have ended up in private hands."
But in recent years there has been something of an Ottoman revival among people living in Istanbul, and with it renewed interest in classic hamams.
Cemberlitas was substantially renovated in the 1980s; Cagaloglu is now on the market for $16m (£9.77m).
The growth of the spa industry around the world has also inspired some entrepreneurs to build new hamams, in shopping malls, hotels and health centres.
"It is very positive", says Ms Ergin. "There is a lot more interest in preserving our historical heritage now, and it is not restricted to more spectacular buildings like mosques. Hamams, and even Ottoman-era factories, are being renovated."
If you happen to have a spare $3m, plus perhaps the same again for restoration, you could buy yourself an authentic Sinan hamam, situated in the historic district of Aya Kapi close to the southern shore of the Golden Horn.
The hamam in Aya Kapi is in need of extensive renovation
It is little more than a pile of stones now; trees have taken root in its crumbling dome, and inside it is being used to store timber.
Estate agent Okan Aksudogan took me up a rickety ladder to see the magnificent brick structure inside the dome.
He believes that for the right kind of investor, at $3m the hamam is a bargain.
"He could probably get his money back, after renovation, in 10 to 15 years," he says. "But the asked price is maybe not the true value, it is just the value put on the business. But what you buy is something unique."
Planning regulations for historic buildings like this are very strict these days. Nina Ergin says that makes it difficult to find investors willing to put in the time and money needed to restore them.
But Mr Aksudogan hopes that either a cultural foundation, or a wealthy individual with a love of classical Ottoman architecture, can be persuaded to bring the Aya Kapi hamam back to its former glory.
(bbc.co.uk , Sunday, 25 October 2009)