Largest walk-through aviary

Birds of Eden, situated near Plettenberg Bay in the Western Cape, South Africa, encompasses a single enormous walk-through aviary occupying an area of 2.3 hectares (5.7 acres). The aviary is covered by 3.2 hectares (7.9 acres) of wire mesh, weighing around 80 tonnes (88 US tons), which is supported by 28 masts of various heights. The estimated volume of the enclosure is 375.4 cubic metres (13.3 million cubic feet). Opened on 15 December 2005, the park is home to some 3,500 birds representing about 220 species, all of which are allowed to roam free throughout the exhibit.

The mesh dome of this free-flight aviary reaches up at 55 m (180 ft) above ground level at its highest point and can be explored via 1.2 km (0.75 mi) of walkways, many of which are elevated allowing visitors to observe birds among the treetops.

It's worth noting that there are larger bird parks, but this record is for the largest discrete single-span aviary.