USP The spa has more treatments (32 to be precise) than a meze platter, from a traditional Turkish hammam to rejuvenating wraps and the latest in skin analysis techniques – Face Mapping by Dermalogica.

AMBIENCE Opened in June 2008, the spa occupies a former 19th-century Ottoman palace and covers 22,605 sq ft - the size of two football pitches. It has adopted Istanbul's East-meets-West philosophy in its design and menu. Contemporary water fountains and directional art mix with understated authentic Turkish design. There’s a beautiful sky-lit, pillared pool with a mosaic tiled floor and underwater sound system, an enormous gym with personal trainers on board, a whirlpool, steam room and sauna.

Marble features heavily in the nine treatment rooms and the three hammams – one each for men and women and one for couples. Staff are gracious and have a way of ensuring your needs are met without you really knowing they are there.

QUALITY OF EXPERIENCE I didn’t really know what to expect when I agreed to have a hammam. Rarely used by the locals since the advent of plumbing, the 21st-century hammam is now the preserve of the tourist wanting to experience a little bit of bygone Turkey. I had visions of a big hairy bruiser scrubbing me to death in front of umpteen naked strangers, but my female therapist, Lisa, asked me if I wanted to keep my knickers on. That was an affirmative.

I entered the circular room and lay down face up on a slab of marble. Lisa doused me with warm water and then proceeded to scrub me with a large textured mitten. There’s something rather odd about having a complete stranger wash you when you’re 40 years old and modest spa goers should think twice before signing up for this treatment as every inch of your body is exfoliated with the prickly glove.

When I turned over I saw the extent of the exfoliation. Dead skin was everywhere and I wondered how it was possible I could be that dirty when I shower every day. Once she’d done my reverse she then covered me in a film of the softest bubbles, gathered in to a sort of pillowcase and squeezed out through the fine material. I was warmly enveloped in thousands of tiny pockets of air making me feel like a human soufflé. This was the best part of the treatment.

A douse of hot water washed them all away and then she gave me a quick and quite vigorous massage. I was invited to sit upright on a bench while she threw more water over me and then dried me off and wrapped me in a towel.

There was the option of hair washing and a visit to the beauty salon afterwards but I didn’t have time so I wore a shower cap to protect my hair.

This is a perfect treatment before an aromatherapy massage because your skin is relieved of all its unnecessary excesses and oils will seep deep into the epidermis.

FOOD There is no separate spa restaurant, but the hotel serves lunch and snacks on the grand courtyard overlooking the Bosphorus or by the outdoor pool. The menu is a fusion of Turkish and Italian and choices include grilled vegetable salad with truffle oil and pecorino shaves; cucumber, tomato, black olives and white cheese salad with pomegranate dressing; a variety of soups, risottos and pastas. The dishes I sampled were excellent.

IN-CROWD Unsurprisingly a mix of upmarket young and old guests from all corners of the globe. The vast conferencing facilities attract business types and the pretty courtyard overlooking the waterfront makes a lovely setting for a wedding.

WALLET WATCH Traditional Ultra Luxury Hammam – 45 mins costs 180 YTL (£72); Dermalogica Face Mapping Age Smart – 60 mins costs 250 YTL (£100); Power Recovery wrap – 30 mins 170 YTL (£68) ; a Palace Bosphorus Room costs €900 (£760).

NEED TO KNOW The Spa at the Four Seasons Hotel Istanbul at the Bosphorus, Ciragan Cad No 28, Besiktas, Istanbul, Turkey 34349 (90 212 381 40 00; www.fourseasons.com/bosphorus)

Kirker Holidays offer two nights at the five-star Four Seasons Hotel in Istanbul from £847 per person, including return scheduled flights, private transfers to and from the hotel and breakfasts. Tel: 020 7593 2288 www.kirkerholidays.com

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