ST. LOUIS -- It is being called the world's largest public zoo sculpture, and the largest sculpture in all of St. Louis -- not counting Eero Saarinen's Gateway Arch.

Renowned sculptor Albert Paley created the "Animals Always" sculpture that opens Friday at the St. Louis Zoo's Hampton Avenue entrance.

The steel sculpture is composed of more than 1,300 elements, stands three stories tall and is 130 feet long. It features more than 60 life-size animals, most of them endangered species.

Paley, 62, of Rochester, N.Y., said the sculpture is "the most complicated piece I've ever done -- it's been about three years from conception to completion."

Paley was the first metal sculptor to receive the Lifetime Achievement Award from the American Institute of Architects, the group's top award to a nonarchitect. In addition to the studio work that originally made his name -- jewelry and candlesticks, for instance -- Paley has designed more than 50 site-specific works. Among them are the ornamental gates for the Smithsonian's Renwick Gallery in Washington and the New York State Senate in Albany.

What makes "Animals Always" exceptional is that it is figurative. Nearly all of Paley's previous works have been abstract.

The idea for "Animals Always" began when St. Louis animal lover Thelma Zalk was on a trip to visit Paley's studio, where she noticed drawings he had made in 1980 for New York City's Central Park Zoo, a project that was never realized.

Zalk recalled thinking, "'We have nothing like this in St. Louis. So let's do it,'" she told the St. Louis Post-Dispatch. She paid $1 million to have the piece fabricated; another St. Louisan, Steven Schankman, paid $1 million more to construct a plaza for the sculpture.

Paley said the work has gone through many changes for its St. Louis site. "The original concept was far less than what we have here, and my skills as a metalworker have grown."

The piece includes two major elements installed in raised beds and a plaza through which visitors will be able to pass.

It will not serve as an entry to the zoo. Those who pass through will face a wall of bamboo and must turn around to exit.

"Our master plan limits us to two entrances," zoo director Jeffrey Bonner said. "We think of 'Animals Always' as much as an entry to Forest Park as to the zoo."

Paley said of the sculpture, "'Animals Always' asks, 'How do we live with other creatures?' I wanted to create a work you walk through and share the space with the animals, which are the same scale as you are. I hope that people will have more sympathy for the need for coexistence among species from experiencing it."