If you look at some of the other photos from the Calgary Zoo that I've uploaded into the gallery you'll see that the river hippos are located directly behind the giraffes. Looking from the other direction (inside), one can view the hippos both above and in an awesome underwater viewing section...and then see giraffes walking around in the background. There are also african crested porcupines, rock hyrax, gorillas, colobus monkeys, etc inside the African area.
To be clear the gorillas colobus etc are in a different building. This particular building houses giraffes, ostrich, hippo, warthog, porcupine, meerkat, hyrax, shorebirds, and pythons.