The area of Australian Antarctic Territory is 5,896,500 square kilometers.

Northern Territory and the Australian Capital Territory. There is also the self-governing external territory of Norfolk Island plus the Australian Antarctic Territory.

Apparently, all Australian states and territories are represented laconically by flowers, some animals, coats of arms and so forth -- except for the Australian Antarctic Territory, which is not represented in these lists.

The Australian Antarctic Territory

Strictly speaking, no country has sovereinty over any part of Antarctica and is on the World Heritage List. Therefore, Australian Antarctic Territory is in name only, not in ownership. That would make Northern Territory the largest official Territory.