The world's most luxurious bathrooms

The private sanctuary where you sink into a soothing bubble bath and the pretty little powder room in which your guests tidy up before dinner may seem like simple spaces. But looks, as the saying goes, can be deceiving," says bathroom designer Barbara Sallick, on her quest for the perfect bath.

It's a journey that's led her and her husband Peter -- the co-founders of bathroom company Waterworks -- to study the bathing habits of ancient civilizations for inspiration.

"Going back to antiquity, we started with the Egyptians, whose obsession with cleanliness was such that they discriminated against cultures whose members didn't follow their own bathing customs,"

says Sallick in the introduction to her new book, "The Perfect Bath."

"The idea of the bath as a font of relaxation, reflection, and restoration, developed by the ancients, is one that has never been improved upon -- all we can do is translate that timeless concept into a

personal reflection of contemporary life," she says.

Designer Pamela Shamshiri believes fine woods deliver healing properties

Sallick takes us on a journey inside some of the world's most beautiful bathrooms, from the simple to the extravagant, to show how one of the most private of spaces can be transformed from perfunctory to a feat of design through the use of color, layering and textures.

And whether large or small, vintage or modern, when it comes to the bathroom, Sallick shows that beauty is in the eye of the beholder.

"There is no one definition of the perfect bath -- precisely because the room is such a singular expression of an individual's (or a couple's) own sensibility," she says

"The master bath is the only space in your home that is all about you -- a highly personalized domain that, in addition to being part of life's daily routine, serves as a private retreat."