The Penthouse
Sydney, Australia
An expansive penthouse home where a modernist legacy meets contemporary luxury, defined by restraint.
Inside a landmark Harry Seidler building is a newly designed home that has responded with precision and sensitivity to one of Australia’s most iconic architectural legacies.
By merging two adjacent sub-penthouses into a singular residence, COX’s interior design team has delivered a sophisticated, fluid and layered interior that respects and elevates its architectural context.
At the heart of the project is an ethos of sophisticated restraint. The design balances minimalist clarity with refined detailing, embracing a warm tonal palette as a base to showcase material contrasts. Jewel-like moments punctuate this calm canvas with walnut-lined spaces, sculptural lighting, and a dramatic bronze bar.
Innovation is found in the project’s nuanced reinterpretation of Seidler’s modernist legacy. While many interiors within his buildings adhere to rectilinear planning, this design introduces rational curves and organic flow. The planning guides movement intuitively, particularly in social zones, where the design subtly choreographs how people gather, move and engage. This curvilinear approach bridges architecture and interior, creating continuity rather than conflict.
Each room offers a distinct mood, making the vast apartment feel intimate and personal. The lounge is moody and theatrical; the bedroom serene and light-filled; the powder room playful and unexpected. This diversity of spatial atmosphere highlights the creative depth of the design, creating an experiential journey through the home.
COX Director, Brooke Lloyd
Designing a home within a Seidler building is a rare privilege. His architecture is defined by clear geometrical forms and functional yet aesthetically rich designs. We wanted the interiors to feel deeply connected to this legacy. Our planning approach centres around rational curves connected to the buildings geometry that create a sense of fluidity and structure through the home.
Functionality is seamlessly integrated. Lighting is fully recessed and sculptural, avoiding surface clutter and enhancing the purity of the architectural form. Joinery is tailored to each room’s use while remaining visually cohesive. A dedicated wine room and entertainer’s kitchen reflect the client’s lifestyle needs, while spatial transitions are handled with grace.
Durable, low-emission materials such as timber, stone and plaster were specified for longevity and minimal environmental impact. The design avoids short-term trends, ensuring the fit-out remains relevant and adaptable over decades. Beyond environmental choices, the project contributes to cultural sustainability, preserving and celebrating Seidler’s architectural vision while reinterpreting it for contemporary life.
In doing so, COX has created more than a high-end residential interior. The Penthouse is an icon within an icon; demonstrating how luxury can be expressive without excess, restrained without being cold, and deeply contextual without compromising individuality.
It sets a new benchmark for Australian apartment living, rooted in design excellence, cultural reverence and intelligent innovation.