Philadelphia Zoo lets tigers roam free on 'catwalk'
8 May 2014 Last updated at 15:49 BST
A zoo in Philadelphia has created a special "catwalk" which allows tigers and lions to roam around freely.
The big cats can now wander around in enclosed, overhead trails across the zoo's visitor pathways.
A similar trail for orang-utans and small primates had been opened at the zoo in the past.
The zoo's CEO Andrew Baker told BBC Radio 5 live's Up All Night: "Once they've all gotten past the newness of it... all the animals have had the opportunity to use it extensively."