Founded in 1896, the Denver Zoo was started with just one tenant; a black bear cub named Billy Bryan. The bear cub was a gift the Mayor, who then turned the cub over to the keeper of the City Park, Alexander J. Graham. Today the zoo is home to 4,000 animals representing over 750 species and is one of the most popular zoos in the United States.

The Denver Botanic Gardens is a public botanical garden located in the heart of Denver just 10 minutes east of Downtown. The 23-acre park contains a conservatory, a variety of theme gardens and a sunken amphitheater, which hosts various concerts in the summer. The Denver Botanic Gardens was one of the first gardens in the country to emphasize native plants and to champion environmentally responsible practices, such as water conservation and biological control of pests. Today, Denver Botanic Gardens continues this tradition at three unique sites: Denver Botanic Gardens, Denver Botanic Gardens at Chatfield and Mount Goliath. Each of these demonstrates the varied ecosystems of Colorado. Most of all, Denver Botanic Gardens offers spectacular plant displays, unlimited opportunities for lifelong learning and research that help preserve Colorado's precious natural resources.

Downtown Aquarium was re-opened on July 1, 2005 as an entertainment and dining complex featuring a public aquarium. Boasting more than one million gallons of underwater exhibits that highlight fascinating ecosystems around the world, the aquarium houses more than 500 species of animals, an interactive Sting Ray Reef touch tank, the Aquarium Restaurant, the Dive Lounge, the Nautilus Ballroom, and amusements for the entire family.