Engineers have uncovered a road built by convicts almost 150 years ago while upgrading Great Eastern Highway in Belmont.
A 20m stretch of road made from big jarrah discs was found under bitumen near Belmont Avenue.
Thought to have been built by convicts in 1867, the road gives an insight into WA's convict history and early infrastructure.
Governor John Hampton ordered construction of the road. Convicts had to lay the wood discs, known as Hampton's cheeses, and fill the spaces with limestone or soil.
State Heritage Office executive director Graeme Gammie said this type of road was Mr Hampton's solution to the problem settlers faced in getting carts to Guildford.
"Often roads because impassable, particularly after rain when people would get bogged, so the governor decided to use this method he had seen in Canada," he said.
"It gives us a really interesting insight into how they dealt with moving people and carts."
The same method was used on what is now Stirling Highway, Guildford Road, Albany Highway and Wanneroo Road in the 1860s.
The State Heritage Office, City East Alliance, City of Belmont and the WA Museum worked together to excavate five pieces of the road in Belmont, including a 5m kerb.
A six-month restoration process is under way to stabilise the jarrah discs, which were acquired by the City of Belmont.
Mayor Phil Marks said the city was committed to preserving its history and would display the road remnants at the Belmont museum.