The world's biggest architecture festival: London Open House weekend 2018 returns for its 26th year this September

Open House London 2018 – billed as the world’s biggest architectural festival – is taking place this month on September 22-23.

Now in its 26th year, more than 800 buildings will open their doors to the public for free, from private homes to corporate offices – even 10 Downing Street.

It’s a fantastic opportunity to see behind the facade and explore the hidden architectural history of the city.

As well as viewing the buildings, participants will be able take part in a programme of walks, talks, tours and rides.

Marking 100 years since women gained the right to vote, this year will see a focus on some of the women who have played a role in shaping London as we know it today with a special collection of buildings whose design is led by female architects.

Open House Families will also return, with activities for children at City Hall.

WHAT'S NEW AT OPEN HOUSE 2018?

New buildings added to this year’s line-up include Bloomberg’s European headquarters. It’s the world’s most sustainable office building and home to the company’s 4,000 employees.

Bridge Theatre is London's first new commercial theatre of scale to be built for 80 years, on a site between City Hall and Tower Bridge, looking over the river to the Tower of London.

Also joining the line-up are the new US Embassy in Vauxhall, which incorporates the latest in energy-efficient building techniques, the refurbished Royal Opera House and the Aga Khan Centre by Fumihiko Maki, featuring six gardens inspired by different parts of the Muslim world.

The Old Waiting Room at Peckham Rye is an old favourite set to return, however Battersea Power Station isn't on the list this year.

The BT Tower, 10 Downing Street and The Shard are also opening again (though you’ll need to enter a ballot to get into those).

To find out more information and to book tickets or enter the ballots for the most popular sites, visit the Open House London website.