Zero Obelisk, survey marker on the east bank of the Warrego River

The Zero Obelisk stands on the east bank of the Warrego River at Barringun, a truncated pyramid of concrete render over stone measuring 0.9 by 0.9 by 0.9 metres. It marks the Queensland–New South Wales border, and part of an inscription on the Queensland side reading "G. WAT" for surveyor George Chale Watson is still visible.

In mid-1879, surveyors from New South Wales and Queensland met at the Barringun telegraph station and began the first official survey of their shared border at this obelisk. Cameron and Watson worked westward to the South Australian border at 141°E, a distance of 235 miles (378 km), taking 12 months and 15 days through flood and drought. Watson withdrew at the hundred-mile post; Cameron completed the section.

The site sits in a remote location near the Warrego River and is accessible to visitors interested in history and surveying. The open landscape means preparation for travel to this rural area is useful before making the trip.

Part of the inscription on the Queensland side of the obelisk still reads "G. WAT", for George Chale Watson, the Queensland surveying commissioner. Watson withdrew at the one hundred mile post because of a lack of water, while Cameron carried on to the South Australian border.