Ten architectural terms you might hear on a Sydney Open tour (and what they mean)

Heading to a Sydney Open tour?

Whether you’re stepping inside a landmark you’ve admired for years or discovering a hidden architectural gem, you might hear guides and experts use terms that don’t often appear in everyday conversation.

Consider this your architectural phrasebook – ten concepts explained that’ll help you make sense of the buildings you encounter.

Adaptive reuse

Not every great building needs to be built from scratch. Adaptive reuse is the process of giving an existing building new purpose while retaining its original character and structure.

Rather than demolishing old buildings, architects adapt them for contemporary needs – transforming warehouses into apartments, factories into galleries, or office blocks into hotels. It’s an approach that celebrates heritage, reduces waste and extends the life of existing buildings.

Machine Hall in central Sydney demonstrates adaptive reuse by transforming a disused 1930s electricity substation and adjoining warehouse into a contemporary arts and cultural venue.

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Sightline

A sightline is the line of vision between a viewer and what they’re looking at. Architects and designers carefully consider sightlines to frame important views and shape the experience of moving through a space.

Sometimes a building is designed to reveal itself gradually; other times, it’s intended to dominate the view from the moment you arrive.

The Glass House in Castlecrag demonstrates how sightlines can harmonise architecture with its surroundings. Its elevated position among the trees and expansive floor-to-ceiling glass walls create uninterrupted views flowing outwards to the landscape, erasing the boundary between inside and outside.

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Density

In architecture and urban planning, density refers to the concentration of people, buildings, homes or other development within a given area. Higher-density places accommodate more people on less land, but this doesn’t necessarily mean squeezing more people into high-rise towers – it can also be achieved through terraces, townhouses or low- to mid-rise apartment blocks. Well-designed density balances development with access to sunlight, green space, transport and community amenities, creating neighbourhoods that are liveable and connected.

Crossroads Marrickville shows how adaptive reuse can creatively increase density on a small footprint: a historic 1890s corner shop transformed into a mixed-use development with a commercial studio, three-bedroom residence, one-bedroom apartment and outdoor courtyards.

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Third spaces

A third space is a place where people spend time outside the two traditional spaces of home (the ‘first space’) and work (the ‘second space’). Third spaces are informal, convenient settings where communities gather, socialise and connect, and range from libraries, parks, community centres and public squares to cafes, gyms, theatres and skate parks. Third spaces are seen as essential to creating healthy, welcoming cities because they foster everyday social connection and anchor a sense of belonging.

PHIVE at Parramatta Square functions as Parramatta’s ‘living room’ – a place where people can borrow books, attend an event, study, meet friends or simply hang out. Combining a public library, civic facilities and cultural spaces, it demonstrates how architecture can create a welcoming third space that brings people together beyond home and work.

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Facade

A facade is the outer face of a building, particularly the side that faces the street or public space. It’s often the first impression a building makes, expressing its style, purpose and character through its materials, proportions and decorative details.

While we might colloquially use ‘facade’ to mean a false appearance, in architecture it’s simply the public face of a building.

The Dr Chau Chak Wing Building at University of Technology Sydney shows how a facade can express a building’s character. The building’s rippling brick facade and glass surfaces create a sense of movement as you walk around it. The combination of materials connects the building to Sydney’s brick and sandstone traditions while giving it a contemporary identity.

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Elevation

If a facade is the front face of a building, an elevation is a view of one entire side. Architects produce elevation drawings to show what a building looks like from the front, rear or either side. If someone refers to the ‘northern elevation’ or ‘street elevation’, they’re describing a particular side of the building.

Parramatta Town Hall’s street elevation presents a composed arrangement of symmetry, columns, windows and decorative details.

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Massing

Massing describes the overall shape, size and volume of a building, and is usually used by architects to discuss the building’s three-dimensional form.

A building can have a simple, box-like massing or be made up of several smaller forms that are carefully arranged together.

Sirius Building in Sydney’s Rocks area is a distinctive example of massing. Instead of one uniform block, the building is made up of stacked, staggered concrete volumes that create terraces, maximise harbour views and reduce the visual bulk of the building.

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Threshold

A threshold is the transition between one space and another – usually between inside and outside. Thresholds shape first impressions, guide movement and signal that you’re entering a different kind of space.

The Mint creates a thoughtfully designed threshold, taking visitors from Macquarie Street through a forecourt, courtyard and historic buildings before revealing contemporary spaces beyond. The journey between old and new becomes part of the architectural experience.

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Atrium

An atrium is a large open space inside a building that often extends through multiple storeys. Many atriums are topped with glass roofs or skylights, allowing natural light to reach deep into the building.

Beyond creating an impressive sense of space, atriums can improve ventilation, encourage social interaction and help people find their way through complex buildings.

The Sydney Trades Hall in Goulburn Street uses a multistorey atrium to usher natural light into the heart of the building.

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Cantilever

A cantilever is a part of a building that projects beyond its supports, creating the impression that it’s floating. Although it might appear unsupported, it’s anchored at one end with the weight carried back into the building’s internal structure, allowing bold overhangs or undercover areas without the need for columns beneath.

The Chau Chak Wing Museum at The University of Sydney uses cantilevered upper levels to create a dramatic sense of weightlessness. By extending the building beyond its supports, the design creates sheltered spaces below while giving the museum its sculptural form.

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The next time you join a Sydney Open tour, you’ll probably hear a few of these terms along the way: the density of a neighbourhood, a cantilever that seems to float overhead or a carefully framed sightline that draws your eye towards the sky. Once you know what to look for, you’ll start spotting these details well beyond a tour – perhaps even on your walk to work!