London Zoo – World's Oldest Scientific Zoo Opened to general public in 1847, this animal abode accommodates 16,000 animals in just 36 acres of land. This is one of the biggest zoos in the world!

In terms of physical land area, the London Zoo (ZSL) is not one of the biggest in the world, covering only about 36 acres in Regent's Park. For comparison, the San Diego Zoo Safari Park spans 1,800 acres. However, the London Zoo is considered one of the "biggest" in terms of historical and scientific significance. Founded in 1826, it is the world's oldest scientific zoo and houses a collection of nearly 20,000 animals across more than 600 species. In 2026, it is celebrated more for its architectural heritage—featuring Grade I and II listed buildings—and its global conservation impact rather than its footprint. If you are looking for a "big" zoo experience in the UK, many travelers head to its sister site, ZSL Whipsnade Zoo, which at 600 acres is the largest zoo in the United Kingdom. While the London Zoo is small enough to explore in a few hours, its density of rare species and its role as a pioneer in zoology make it a heavyweight in the global conservation community.