Think Tank is an exhibit that evolved out of a desire to renovate the Monkey House. When the decision was made in 1990 to renovate, Zoo staff wanted to change the theme of the monkey exhibit, but still include primates. The historic building preservation restrictions also made the exhibit unsuitable for a large group of great apes that would live only at Think Tank. One idea was to build an exhibit about evolution, but the idea was not enacted because there was already an evolution exhibit in the National Museum of Natural History. The discussion then turned toward developing an exhibit on cognition.
The Zoo staff chose to use orangutans as the star primate since renovations would provide the animals with more enclosure space and enrichment activities. One person suggested building a tower for the apes so they would have more space and a new view of their surroundings. One problem that remained, however, was getting the orangutans from the Great Ape House to the new exhibit space. The idea eventually evolved into a series of towers connected by cables that would allow the orangutans to move back and forth from the Great Ape House to their new building. The "O Line," as it is now called, allows visitors to see orangutans in an arboreal mode as well as providing enough space for the orangutans in a building with historic preservation restrictions.
The building that houses Think Tank is the oldest building still in use at the National Zoological Park. It was completed in 1906 at a cost of $40,000. The building first served as a House for Small Mammals, then as the Monkey House, and now as Think Tank. Over the years, the building has undergone many renovations, but the building's exterior has changed little.
In 1904, James R. Marshall and Joseph C. Hornblower, architects of the Natural History Museum on the National Mall, were commissioned to design the building. The original building was 135 feet x 60 feet (41.2m x 18.3m). The building exterior was built using Kensington gneiss, a "salt and pepper" metamorphosed granite quarried locally. Marshall and Hornblower wanted to use brown-glazed brick faces with panels of brightly colored bricks, but the design review team overrode their idea.
The roof of the Think Tank building was done in clay tiles in varying shades of green with purple glass used as skylights for the enclosures. Fox, lynx, and bear figures were placed on the nine pointed gables. The figures were designed by Laura S. Kemeys, a watercolor painter, and produced by the Perth Amboy Terra Cotta Company.
The building was renovated in 1975. The enclosures were expanded and walled with glass on the interior and the public space was opened up. The 1975 renovation cost $600,000. Some changes were also made in 1983.
In 1995, the monkey house was renovated to create the Think Tank exhibit. Because the Zoo is designated a "historic site," all construction and renovation at Think Tank had to be reviewed by the Historic Preservation Review Board and the National Capitol Park and Planning Commission. Construction restrictions were placed on the modifications to the original building. The modifications that were permitted had to conform to the building's original style. Exhibit space was added in the rear of the building and other parts of the interior were also changed. Coastal Design, Ltd. did the design work and the Ronald Hsu General Construction Co. was the primary contractor for the exhibit. Approximately $4 million in federal funds and private and corporate contributions were used on construction and exhibit elements.