Sydney's architectural landscape is a testament to its rich history and cultural evolution, beginning with the early structures built to minimal standards in the colonial era. Under the leadership of Governor Macquarie, ambitious standards for construction were established, resulting in a city that boasts a World Heritage-listed building, numerous national heritage sites, and countless Commonwealth heritage-listed structures that stand as a testament to Macquarie's vision.

York Street exemplifies Sydney's Victorian heritage, showcasing an impressive array of preserved architecture. In 1814, Governor Macquarie commissioned convict architect Francis Greenway to design the Macquarie Lighthouse. Its classical design earned Greenway a pardon and marked the beginning of a refined architectural culture that persists today. Greenway’s subsequent projects, including the Hyde Park Barracks (1819) and St James's Church (1824), further enriched Sydney's architectural identity.

The 1830s saw a rise in Gothic-inspired architecture, exemplified by John Verge's Elizabeth Bay House and St Philip's Church (1856), as well as Edward Blore's Government House (1845). Other notable examples of Victorian Gothic construction include Kirribilli House (1858) and St Andrew's Cathedral, Australia's oldest cathedral.

From the late 1850s, a shift towards classical architecture emerged, with Mortimer Lewis designing the Australian Museum in 1857 and James Barnet overseeing the completion of the General Post Office in 1891, which featured a Victorian Free Classical style. The neo-Classical Town Hall was completed in 1889, while the Queen Victoria Building (1898), designed in Romanesque Revival style by George McRae, became a vibrant shopping destination.

As Sydney's wealth increased post-Federation in 1901, the cityscape transformed, leading to taller buildings. The Culwulla Chambers, Sydney's first tower, reached 50 meters (160 ft) with 12 floors, followed by the Commercial Traveller's Club in 1908. The lifting of height restrictions in the 1960s sparked a high-rise construction boom, dramatically changing the skyline.

The Great Depression influenced architectural trends, leading to more restrained designs. The Harbour Bridge, completed in 1932, became an iconic structure, showcasing engineering prowess with its 39,000 tonnes of structural steel spanning 503 meters (1,650 ft).

Modern architecture began to take root in Sydney in the 1940s. The Sydney Opera House, completed in 1973, has since become a World Heritage Site and a global icon of modern design, earning architect Jørn Utzon the prestigious Pritzker Prize in 2003. Another contemporary highlight is the Dr Chau Chak Wing Building, completed in 2015 by renowned architect Frank Gehry, marking a significant addition to the city's architectural diversity.

The Central Business District (CBD) features an array of contemporary buildings, including the Citigroup Centre, Aurora Place, Chifley Tower, and Sydney Tower, the latter designed by Donald Crone and completed in 1981, which stands as Sydney's tallest structure at 330 meters (1,083 feet). This height is regulated due to the proximity of Sydney Airport, ensuring the preservation of the city's unique skyline.

Since the late 1970s, green bans and heritage overlays have been enforced to protect Sydney’s architectural heritage, particularly following controversial demolitions that highlighted the need for preservation. Today, Sydney’s architecture continues to celebrate its past while embracing innovative designs, creating a vibrant and dynamic urban environment.