@Wyman The rocks form a artificial kopje - there's grass covered ground on the floor of the exhibit. Every time I visit, the lionesses are always on the kopje - either asleep or surveying the crowds; but the males (before their move to Auckland) were often patrolling the exhibit. They seemed to spend less time on the kopje - but loved it nonetheless.
My favourite thing about Wellington Zoo's lion exhibit is that you can view it from two levels - eye level to the kopje - as seen in this shot; or at the ground level viewing window.
@Wyman the photo below shows some of the ground area. It's not a large enclosure overall. The indoor housing is under the kopje and is accessed by the keepers at the left side of this photo (the metal "cage" beside the tree is the safety entrance); the lions' area stops about where the left side of the photo is. However the enclosure loops around the far side of the kopje and onto the hillside behind - I'm not sure how large the rear area is because it was never accessible to the public, although you used to be able to see part of it from one of the paths (now closed off).
There are three places to view the lions - from the side of the enclosure (the photo below), from the top over-looking the kopje (the photo above), and through a viewing window in a "cave" at ground level directly in front of the kopje (out of view on the right side of the photo below).