The simple bathrooms of ancient India, Egypt and Mesopotamia were all rudimentary showers. They did not contain baths, and people washed by pouring water over themselves or having it administered by a servant standing behind a low wall.
But the first real showers, with plumbed-in water, were invented by the ancient Greeks. After exerting themselves in the stadium, ancient Greek athletes would freshen up in the kind of shower depicted on an Athenian vase of the fourth century B.C. Two shower rooms are shown, occupied by four rather muscular young ladies. Piped-in water sprays down on the bathers through showerheads shaped like the faces of boars and lions. Near the top is a rack or pole over which the girls have draped their garments and towels. The whole scene is amazingly contemporary: apart from the animal showerheads, it would not be out of place in a modern gym.
The remains of a whole complex of shower-baths were excavated in a gymnasium at Pergamum, a rich Greek metropolis in Western Turkey. The last phase of its construction dates to the early second century B.C., at which time seven bathing units were in use. Water ran from an overhead mains system onto the bathers and then flowed from one bath to another, running from the last one into a drain. Thus the system, like a modern shower, provided a footbath as well.
Read about other ancient inventions that shaped history and paved the way for modern inventions.