The Detroit Zoo, in Royal Oak and Huntington Woods, is a 125-acre institution owned by the City of Detroit and operated by the Detroit Zoological Society. Opened in 1928 after an earlier, short-lived 1883 zoo in Detroit, it became the first zoo in the United States to use bar-less habitats, reflecting its long emphasis on animal welfare and conservation. Over time it developed notable exhibits, from early bear, bird, and primate houses to major modern habitats for polar bears, amphibians, penguins, kangaroos, and great apes. Its later history includes ending elephant keeping on ethical grounds, stabilizing funding, and adding sustainable waste-to-energy systems.