BEHIND THE SCENES: Go inside the Crown Fountain

On a hot summer day in downtown Chicago, expect lots of "splashing around" at the Crown Fountain, as 10-year-old Lexi Peponis pointed out.

"It's cold," added 8-year-old Kate Jenny.

The fountain's faces stare down on crowds, spitting every few minutes on eagerly waiting kids.

That's what happens outside the fountain. But Millennium Park Foundation Executive Director Scott Stewart gave me an expanded tour, taking me where the water disappears underground.

Directly beneath the two towers, within the park's parking garage, are pump rooms where the water flows from above.

"The water is flowing down from above us in crown fountain, down through these large pipes, through this filter unit, and then it is being drawn through this pumping unit that you see right here," Stewart explained as we walked through the north tower's pumping room.

He said along the way the water is chlorinated and pH balanced "simply because people play in the fountain."

"We lose water through evaporation and drips and drains," he explained, adding that "this fresh water supply tops off the total amount of water every day."

After that stop we climbed up a ladder, through a hatch, and into the fountain itself. Unlike the constant rumbling outside the towers, there's serenity within. Little noise as the water streams down the sides from 60 feet up.

Stewart pointed out the "Gargoyle Supply" which helps "the face with the spitting."

Also inside the towers, "the LED screens that do the face projecting... Each level is a level to check and do the maintenance on each of the LED panels," said Stewart.

Finally, there's the control room with a computer system constantly selecting two of 1,000 faces to project on the towers.

"These face were hand selected based upon a large pool of volunteers. They're all Chicagoans. They're hand selected by the artist, Jaume Plensa... You will never see the same face on the north and the south towers... However, no matter what the faces are... they both spit at the same time."

Keeping Chicago cool all summer long!