The confining steel bar cages have been replaced with flourishing fauna and waterfalls, and now visitors can now view these wide-eyed cats in their natural habitats. Opening tomorrow, Bank of America Big Cat Falls at the Philadelphia Zoo will give visitors a more intimate sense of wild cats in the nation's oldest zoo.

Visitors will be up close and personal with lions, pumas, tigers, leopards and jaguars.

Lounging in the sun, the zoo's pride of four lions, including male Merlin and females Zenda, Jezebel and Vinkel now inhabit about 6,000 square feet of "African" territory.

"The lions can stay outside year-round because we've installed hot rocks, which stay warm throughout the year," says Kristin Lewis, director of public programs at the zoo.

A system of overhead tunnels will allow the cats to move from one exhibit to another.

"Being able to smell and explore a space where another cat has lived will provide excellent behavioral enrichment," explains Lewis.

In addition to animal exhibits, Big Cat Falls offers training demonstrations, high-definition video displays, interactive computer presentations and lots of focus on conservation.

The pavilions feature a sliding door that opens onto a small, steel-mesh enclosed area where zookeepers will demonstrate behavioral techniques.

"It's an opportunity for people to see, right up close, the work we do with the animals. It gives the animals a higher standard of care," says Lewis.

If you go: The Bank of America Big Cat Falls opens tomorrow at the Philadelphia Zoo at the corner 34th Street and Girard Avenue in Philadelphia. For more information, visit www.philadelphiazoo.org.