Set within nearly 60 hectares of bushland on ’s northern edge, the Southern Lookout is the first architectural intervention in the staged transformation of the former Hornsby Quarry into Hornsby Park.
Designed by , the 42-metre-long structure reaches out towards the quarry void, offering the public a new way to engage with a that has been inaccessible for more than a century. Expressed in weathering and carried on a minimal structural footprint, the lookout is both a viewing platform and an interpretive threshold: a place where geology, industry, bushland and civic renewal converge.
We spoke with Lee Collard, Studio Director at AJC Architects, about restraint and designing at the edge of a dramatic former quarry.
Can you tell us about the site context of the Southern Lookout?
The Southern Lookout is situated within nearly 60 hectares of bushland surrounding a former rock quarry on Sydney’s northern edge in Hornsby. The site is defined by a striking juxtaposition of exposed volcanic diatreme geology, undulating sandstone bushland and Blue Gum High Forest.
Located just a 15-minute walk from the evolving Hornsby town centre, the site has been closed to the public for over a century.
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What was the broader brief for the project?
Hornsby Shire Council is transforming the former quarry and its surrounds into a regional destination — Hornsby Park — where bushland, dramatic quarry walls and the quarry lake become the defining experience.
Guiding the approach to reopening, reconnecting and rehabilitating the site is a Council-adopted, landscape-led masterplan by Clouston Associates, which establishes a clear and ambitious vision for its staged transformation.
The lookout is the first architectural intervention within this transformation: a 42-metre-long structure that introduces a new way for visitors to engage with both the natural landscape and the site’s past.
When was the project completed and how does it sit within the wider development of Hornsby Park?
Civil works to stabilise and secure the quarry void commenced in 2022. The Southern Lookout was completed in late 2025, with the Crusher Plant Precinct and Southern Lookout opening to the public in April 2026.
The next stage, Old Mans Valley, which includes the entry plaza, field of play and supporting amenities, is currently under , with completion anticipated in 2028.
What were the key material and structural choices?
The project is driven by the ambition to maximise reach and outlook while minimising material use and disturbance to the site. Material selection and structural expression reinforce the conceptual intent, drawing from the quarry’s industrial character.
The 1.4-metre-deep weathering-steel edge members are not just balustrades; they become the long-spanning structure, carried on a minimal number of angled supports that touch down together in the bushland.
That efficiency in material and fabrication enabled the length of the platform — and with it, a greater reach and a stronger encounter with the quarry void.
Simply, the weathered appearance, large span carried on angled columns, and reaching cantilever not only resolve the engineering; they also define the lookout’s character, presence and quiet drama.
What key functional requirements did the design need to address?
At its core, the project is about opening the site to the public, introducing access into what was previously an inaccessible landscape.
The design uses movement, view and controlled revelation to shape how the site is experienced, allowing visitors to gradually understand its scale, stories and the transformation underway. It works as both a physical and interpretive framework, connecting people to the character and memory of the place.
It was also important that the project minimise its impact on the landscape. The design reduces excavation and limits its footprint within the bushland, with most of the structure prefabricated off-site to further reduce disturbance. At the same time, it adopts a robust, low-maintenance material approach, using durable, recyclable elements designed for longevity.
What are your favourite moments in the finished design?
The built outcome is expressive yet restrained — an industrial remnant in character, settled within the bushland rather than set upon it.
The experience is deliberate and evocative, moving from ground to void, enclosure to exposure, and containment to expanse. It reveals the scale, drama and distinct character of this spectacular place.
AJC Architects
Photography
Alexander Mayes
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