29/10/2026
The Border Cairn (Todd's Obelisk) is the Eastern-most State Heritage Place in South Australia. The Border Cairn was built by the Government Observer (Astronomer) at the time, Sir Charles Todd in 1868. It marks the border between South Australia and New South Wales and demonstrates not only the history of surveying in South Australia but is a representation of the physical identity of the State itself. Todd was tasked with correcting a surveying error from as far back as 1839 and identified the new border using a combination of astronomical readings and telegraphic links with Sydney and Melbourne.
Image: NSW/SA Border obelisk with Douglas Robertson on a motorbike, c. 1920. State Library of South Australia [B 49427].