Kansas City Zoo is building a new rain forest, and they are retaining the old building. That's great to see.

Video | Building a rainforest at the KC Zoo

It’s below freezing today, but the Kansas City Zoo is building a rain forest.

The original 1909 building that once housed the entire animal collection has been gutted to be refitted as the centerpiece of the animal park’s centennial this year.

The key elements will be lush foliage, flowing water, natural daylight and monkeys.

Lots of monkeys.

“Everybody always asks, ‘Where are the monkeys?’ ” said zoo director Randy Wisthoff. “Kids love ’em.”

The zoo plans to open the exhibit in early May as the main event in a yearlong “Zootennial” celebration. Docents are preparing displays to show the zoo through the decades, including vintage photos of the first building that look embarrassingly dated to modern eyes.

“One cage housed the tiger and the next cage the bear,” said Kathy Smith, a Friends of the Zoo board member working on centennial events.

Even the visitors look different.

“The women were all dressed up in high heels and hats,” Smith said.

The new tropics exhibit is designed to look as natural as possible, with several waterfalls.

The zoo is dispatching a buyer to Florida next month to purchase exotic plants, including orchids and banana trees.

Most recently, the 1909 building was a children’s education center.

The floor of the building was lowered by four feet to increase the height of the exhibit space. The flat roof, installed during a renovation in 1969, is being replaced with a vaulted skylight evoking the original gabled roof of the building. Several other skylights will flood the interior with sunshine.

The plants and animals will represent tropical areas of South America, Asia and Africa. Among the several species of primates will be white-cheeked gibbons, whose hoots and hollers will be audible outside.

Crested screamers, whose call is said to be the loudest of any bird, will add to the jungle noise.

Other species will include the capybara — the world’s largest rodent — toucans and a type of anteater.

A highlight of the exhibit will be a glass-enclosed bridge. Visitors will be able to watch monkeys swinging on vines above their heads and Asian small-clawed otters swimming beneath their feet.

The $5.1 million project is funded with general obligation bonds approved by voters in 2004. It will include 8,000 square feet of exhibit space and 5,000 square feet of back space for animal holding, food preparation and other management needs.

There is plenty of room to the west of the building for expansion.

Maintaining a tropical climate will require a lot of energy, but Wisthoff said he hopes the exhibit will draw more people to the zoo to cover the costs. The building is close to the zoo entrance and will be a warm attraction year-round.

When the zoo opened in 1909, the collection included four lion cubs, a wildcat, three monkeys, a badger, a wolf, a fox, a coyote, a lynx, an eagle and smaller birds. The building was intended to eventually be a birdhouse, to be followed by other buildings. But those plans did not materialize, and by 1926 the building housed tigers, leopards, Asian elephants and a hippopotamus.

The bear grotto was added in 1912 and expanded in 1932. Major additions were made every few years until a 20-year dry spell began in the 1970s. A voter-approved bond issue allowed construction of an Australian section in 1993 and an African section in 1995.

Zoo officials say they need to continue to improve the zoo and add attractions to boost attendance.