It’s possible you don’t know that the building you spend your nine-to-five in was once Australia’s tallest. Or that the cafe you grab your morning coffee from is the most-intact Late Georgian townhouse in New South Wales. Welcome to Sydney Open, returning for its 12th year to educate locals about their city.

Access spaces normally off limits when the doors to some of Sydney’s most architecturally and historically significant buildings are thrown open for one weekend.

One of Australia’s most sustainable and environmentally-friendly buildings in Sydney, 200 George Street, is designed to respond to its workforce in an organic way. Spanning 39,200 square metres, the EY building cost $600 million to build and you’ve been invited inside. Alternatively, walk through the Parliament of New South Wales and peak into legislative rooms, which have been in action for over 150 years.

The initiative has been run by Sydney Living Museums since 1997.

“Sydney Open is a weekend to celebrate the city’s architectural history,” says Dr Caroline Butler-Bowdon, director of curatorial and public engagement at Sydney Living Museums. “We can become sticky beaks in our city. We try to have a combination of the old and new, heritage buildings right through to Barangaroo.”

This year we’re invited to explore five new buildings including the Australian Museum and the Two International Towers at Barangarooo. Focus tours are also back by popular demand. For an extra fee, ticketholders can delve deeper with guided tours of some of Sydney’s most elusive buildings such as St James’ Church Bell Tower which was designed by the colony’s first Government Architect, Francis Greenway, and built by convicts. “Think underground tunnels, bell towers and small spaces that are off limits,” says Butler-Bowdon.

The event will run over two days. Focus tours take place on Saturday November 5 and free roaming tours are offered on Sunday November 6. Sydney Open encourages ticketholders to photograph every corner of the structures they walk through.

For tickets and further information visit sydneylivingmuseums.com.au/sydneyopen.