Open House Worldwide is a network of 60 organisations hosting festivals and dialogue about architecture, design, and cities across the globe. In 2023, 1.2 million people visited one of the 6,250 buildings and activities part of an Open House festival thanks to the help of 14,460 volunteers. Collectively, Open House Worldwide is the largest celebration of the urban landscape in the world. The network was founded and is administered by Open City, a charity registered in the United Kingdom.