Currently the building has three enclosures with two viewing areas in between, the sliding doors to which you can see on the far right and in the back left of the picture. Currently this building is home to, as seem from back to front in this picture, a mother and a daughter of Queensland koalas (the breeding male died last year and was kept together with the pademelon), a Goodfellow's tree kangaroo and a dusky pademelon.
This building was originally built as a kangaroo house by Emile Thielens in 1898, then with mesh cages instead of glass enclosures. In later years it was used to keep various kinds of smaller mammals. I personally remember that in the late nineties and the nillies it at various times or throughout the whole period held babirussa, binturong, blue duiker, genet, African brush-tailed porcupines and fennec fox.
In 2008-2009 the building was renovated and repurposed to hold a breeding center for the Congo peafowl (a species first kept in captivity at Antwerp Zoo and for which Antwerp Zoo coordinates the EEP) as well as some other (West-)African birds. That destination however only lasted about 6 years. Exactly why the Congo peafowl breeding center at this location was scrapped I do not know. At that time the Congo peafowl were moved behind the scenes and while they are still kept and attempted to be bred at both Antwerpen and Planckendael, they haven't been visible to the public anymore since that time, which I personally regret. I still hope at least one pair of the species will at some point be visible to the public again (perhaps in the new bonobo building at Planckendael?).
In any case the building was renovated and repurposed again in 2014-2015 to hold marsupials again - including a small kangaroo. A partial return to the building's late 19th century form, function and aesthetics, as it were. Personally I like the current form of the building and the enclosures, even if they are admittedly not very big.