This weekend the doors of some of London’s most creative, intriguing and historic buildings will open to the public for free for the 21st year.

But in 1992 when Victoria Thornton started Open House London and looked for participants the response was “No, no, no”, she says.

Today the concept has “snowballed” to include 20 cities around the world.

And even that most famous of houses 10 Downing Street opens later.

Continue reading here.

(Published 21 September)