Hilbert Conservatory (White River Gardens, Indianapolis Zoo)

The idea goes back to the early 1990s, when Indianapolis Zoo officials wanted to show how plants and animal habitats depend on each other. Jeffrey Bonner, hired as the zoo's president in January 1993, envisioned adding a botanical garden.

Funding came together over a few years: the Lilly Endowment granted 5 million dollars in December 1996, and Stephen and Tomisue Hilbert pledged 3 million in April 1997, which gave the conservatory its name. The whole project cost 15 million dollars. White River Gardens opened to the public on 13 June 1999; the zoo has run them from the start, and since 2007 a single admission covers both.

The gardens now serve as the zoo's main entrance. The conservatory itself has been closed for a complete overhaul: called Rainforest Discovery, the new exhibit is to turn it into an Amazon-inspired rainforest. The zoo's website announces an autumn 2026 opening, although the header of one of its pages says 2027.

Designed by the Indianapolis firm Woollen, Molzan and Partners, the conservatory is a fully glazed building of 5,000 square feet, about 465 m², with ceilings rising to 65 feet, close to 20 m. The zoo describes a gleaming shape that stands out against the night sky and answers the downtown skyline while recalling Indiana's agricultural heritage.

A mezzanine gives raised views over the indoor plantings and the outdoor DeHaan Tiergarten. Along the north end, blown-glass windows are the work of artist Dave McLary, while a central font by sculptor Dale Enochs fills the space with the sound of flowing water. The 3.3 acres (1.3 ha) of gardens around the building were laid out by the landscape architects Rundell Ernstberger Associates.

Before it closed, the conservatory brought together exotic palms, ferns, orchids and bougainvillea around a fish pond. It featured the ʻālula (Brighamia insignis), a Hawaiian succulent extinct in the wild that now survives only through propagation in botanical gardens. Butterflies and bonsai made seasonal appearances, and the annual Butterfly Kaleidoscope exhibit showed more than 13,000 butterflies of over 40 species.

The new exhibit combines tropical vegetation with animals from forest floor to canopy: Hoffmann's two-toed sloths, armadillos, tamanduas, macaws, red-footed tortoises, tree frogs and freshwater fish including red-bellied piranhas and neon tetras. Butterflies are due to return with the opening. In 2021 White River Gardens as a whole held 47,233 plants of 3,055 species.

The conservatory stands in White River Gardens, on the banks of the White River in White River State Park, close to downtown Indianapolis. The gardens now form the zoo's entrance: after the Colts Welcome Plaza, visitors walk through them before reaching the animal exhibits.

It is worth checking that the conservatory has reopened before planning a trip. Outdoors, 1.5 miles of paths link the nine themed gardens of the DeHaan Tiergarten, with fountains and sculptures, best seen from spring to autumn. In autumn the ZooBoo festivities enliven the site. A visit naturally pairs with the zoo itself, included in the same ticket.