Elephants:

Enclosure and holding space: Indoor space should provide adequate room for animals to move about and lay down without restriction. A minimum of 400 sq. ft. (37.2 sq. m.) is required for a single animal. Because of their greater size or space requirements, bulls or cows with calves should have at least 600 sq. ft. (55.8 sq. m.). Mature animals can reach 20 feet (6.1 m.) vertically and ceiling heights must exceed this distance. Retaining barriers such as walls, moats, and railing should also be constructed with these abilities in mind. Generally 10 12 feet (3.1 3.7 m.) should be allowed horizontally between barriers and unprotected areas.