Have you ever noticed a small brass plaque set into a footpath or road and wondered what it was?

Chances are you’ve spotted a survey mark—one of thousands spread across Victoria that quietly underpin everything from property boundaries to major infrastructure projects.

What is a survey mark?

A survey mark is a permanent reference point placed by a surveyor at a precisely measured location. They may be brass plaques, metal pins, concrete monuments or other permanent markers, each forming part of a network of known positions used by surveyors.

Think of them as the GPS checkpoints of the surveying world. They provide reliable reference points that allow surveyors to accurately measure land, establish property boundaries and ensure new projects are built in exactly the right place.

Some survey marks are older than you might think

Not every survey mark you see is new. In fact, some have been in place for well over 100 years.

Many marks were established as Victoria was first being surveyed and settled. Over the decades, roads have been widened, footpaths replaced and landscapes changed, but survey marks have often remained exactly where they were originally placed. It’s not uncommon for older marks to now sit beneath layers of asphalt or concrete, hidden from view but still carefully documented and able to be recovered when needed.

These historic marks form part of an unbroken chain of surveying information that connects today’s measurements with those made generations ago. By preserving them, surveyors can compare old and new surveys, confirm property boundaries and maintain the accuracy and consistency of Victoria’s cadastral system over time.

Why are they so important?

Survey marks are fundamental to almost every land development and construction project.

They help surveyors:

• Define legal property boundaries.
• Plan and construct roads, railways and bridges.
• Design new housing estates and buildings.
• Map utilities such as water, gas, electricity and telecommunications.
• Monitor movement of structures, coastlines and the natural environment.

Without these permanent reference points, every survey would effectively have to start from scratch, making projects slower, more expensive and less accurate.

They’re protected for a reason

Because survey marks are the foundation of Victoria’s surveying system, they are protected under legislation.

Even an older mark that appears unused may still play an important role. Surveyors often rely on historic marks to retrace original property boundaries, verify previous surveys and connect modern surveys back to the state’s long-established survey network. Once a survey mark is destroyed, that physical link to the original survey is lost forever.

For this reason, damaging, removing or disturbing a survey mark without proper authority can attract significant penalties. Before construction, excavation or demolition work begins, licensed surveyors identify and protect existing marks—or, where removal is unavoidable, follow strict procedures to replace them and preserve the integrity of the survey network.

What should you do if you find one?

The best thing you can do is simply leave it where it is.

It might not look particularly exciting, but that small marker could be helping surveyors deliver the next road upgrade, school, hospital, housing development or community project—or preserving a record of measurements made more than a century ago.

So next time you’re walking down the street and notice a mysterious brass disc under your feet, you’ll know it’s doing an important job—quietly helping surveyors connect the past with the future and ensuring the world around us is measured accurately.

Sometimes the smallest pieces of infrastructure have one of the biggest roles to play.