Blue plaque: Five facts about London's blue plaques
Blue plaque number 1,000 has been unveiled in what is thought to be the oldest commemorative plaque scheme in the world.
The 1,000th plaque commemorates the Women's Freedom League and is located at the organisation's former headquarters at 1 Robert Street, just off the Strand.
The London scheme, now run by English Heritage, put up its first plaques in 1867.
Since then a blue disc has become a well-known symbol to celebrate people and the buildings they lived or worked in.
Still going strong after more than 150 years, here are five facts you might not have known about the blue plaque scheme.
Video by Sameena Misbahuddin