Deep beneath the Eiffel Tower, Fabrice Fevai dodges fat water drops, skirts slick pools on the concrete floor and dodges giant wheels and pistons.

Deep beneath the Eiffel Tower, Fabrice Fevai dodges fat water drops, skirts slick pools on the concrete floor and dodges giant wheels and pistons.

"Down here there's always water dripping, we always have leaks," he says.

Splat. His shoulder takes a direct hit.

It's 3:15 in the afternoon, throngs of tourists are lined up topside, one elevator is down for repairs and Fevai is the man in charge of keeping the two others going. Each one lugs thousands of tourists up and down one of the world's most recognized landmarks every day: a hundred trips up and down the cable, 92 gawking tourists each load, countless cameras clicking to preserve priceless vacation memories.

Fevai, 47 and soft-spoken, is an engineer who got his training running ski lifts at some of France's premier resorts. He now walks his beat underneath 7,300 tons of iron spider-webbing. His domain is the subterranean maze of hydraulic pistons and pulleys, more than a century old, that hoist the elevators to the bird's-eye view of Paris atop the tower. His title is chef du service — head of services — for the Society for the Operation of the Eiffel Tower.

When the massive, water-fed hydraulic elevators were installed in Gustave Eiffel's creation for the 1889 world's fair, the cable cars were at the cutting edge of technology, among the largest hydraulic lifts in the world. Today these antiques serve one of France's most popular monuments, with more than 6.7 million visitors last year.

The pistons are greased with pig or ox fat mixed with hemp fiber. The insides of the taps on the water pumps are lined with leather saturated in ox-hoof oil.

"The original machinery needs the original grease — it won't work with modern oils," Fevai says, leaning over to inspect the thick, translucent globs of pig fat oozing down the sides of a pipe casing. "It's been like this for over 100 years."

Today, in an age of refined oil lubricants, the grease is hard to find, Fevai says. Fortunately, a company in northern France still produces the obsolete animal fat concoctions. Fevai orders it in 13-gallon jerrycans.

A nearby wall is lined with wrenches the size of a large man's thigh, tools perfect for the hands of Paul Bunyan. They're used to tighten century-old bolts with rusting heads the size of cauliflowers.

Just around the corner is the computer room, with blinking screens, banks of computers, and rows of buttons and switches. "It's a job of contrasts," Fevai says. "In here, I have to handle tiny screwdrivers. Out there it's the huge tools from another era."

The computers are a relatively new addition.

A human conductor used to sit on the outside of the cable cars ferrying passengers up the tower. Security and safety regulations replaced him with a button and a computer two decades ago. There's now a mannequin in his place, just for looks.

It's not been easy teaching the computers to think like a wizened human, Fevai says.

"Nowadays we have to adapt to replacing the old guy driving the elevator with a computer system that isn't intelligent," he says. "You have to feed the machine the driver's knowledge."

The conductor knew his elevator and its moods. He knew when it was cranky. The computer can't read cantankerous cars. Maintenance workers have to check the elevators several times before each takeoff to make sure the doors have closed properly, Fevai says.

An electric elevator was added in the 1960s. It's the one that's now undergoing repairs, having its cables replaced. Usually it's the more reliable lift, requiring only 15 minutes of maintenance each morning, compared with the hour of prep the two hydraulic lifts need. It also carries more people.

"It's less charming," Fevai concedes. "But the purpose is to get people up. You need to be efficient."

He nods toward the computer screen streaming the live 4:25 p.m. shot of camera-toting tourists packing into the elevator above.

A few minutes later, the underground cavern shudders as pistons send the car climbing skyward.

The public used to be allowed to tour Fevai's collections of wheels and pulleys and pistons. Security concerns ended that about the same time the computers were installed. France granted an exception this past weekend when it celebrated heritage days and opened hundreds of closed sites — including the inner workings of the Eiffel Tower — to the public.

Fevai heads back up to the open-air plaza.

"People enter the Eiffel Tower as though it's a monument with lots of iron," he says, threading his way through a sea of milling tourists. "But the Eiffel Tower is like a factory — they don't even realize what's underneath."

Washington Post researcher Corinne Gavard contributed to this report.