The restorative powers of water -- hot water, bubbling water, and mineral-rich water -- have been celebrated for centuries.

Public baths, dating back 4,500 years, have been found in Pakistan, and ancient Babylonians and Egyptians also took to the waters of public baths for rejuvenation.

Baths are a significant part of the Roman archaeological legacy, from Rome itself to Aquincum, Hungary, and Bath, England. And Roman baths anticipated today's spas, with hot and cold pools, steam baths and massages.

During the Middle Ages, baths in Europe fell out of favor with the public. But during the 17th and 18th centuries, the medical establishment renewed its -- and the public's -- faith in the benefits of visiting a spa.

By the 1800s, Europe's ruling classes had the wealth and leisure time to retreat to curative spas for months on end, socializing in-between underwater traction sessions and other treatments.

As the upper class took the plunge, towns like Baden-Baden in Germany, Karlovy Vary in the Czech Republic, and Vichy, France, became renowned spa resorts, capitalizing on the interest from the elite. Spas caught on in the United States as well, from the hot springs of Hot Springs, Ark., to the mud baths of Calistoga, Calif.

Today's spa taps a variety of cultures. The medieval Turks created the five stages of the spa bath experience still practiced today: dry heat, moist heat, massage, cold and then rest. The Finns contributed the unique practice of sweating and hitting each other with fir branches in the sauna.

Modern spas reflect knowledge accumulated from these early practices, and offer a variety of services. Want a massage? Swedish massage, Shiatsu, Esalen and reflexology are only a few of the choices. A bath? There's cold, warm or hot water; fizzing, bubbling, or whirling water. There's even water that buoys you up through high concentrations of Epsom salt, sulfur, magnesium, boron or iron. You can also "bathe" in steam or slip into a mud bath. Or you can douse yourself with shocking cold water while enduring the relaxing heat of a sauna.

Today, spas are enjoying a resurgence, with "day spas" opening in cities across the country appealing to those with little time for weekend or week-long escapes. And with more spas comes increased competition, which in some cases can mean more competitive prices. Spas are increasingly becoming more accessible to the masses, and have tailored their services into packages offering more for less.

Spas