Britain declared war on Germany on 4 August 1914.

"We are putting art and culture at the very centre of the whole project," said Tamsin Dillon, curator of Lights Out. "It is about marking the moment that Britain joined World War One with the idea of a single source of light replacing all other kinds of light."

The Lights Out campaign was inspired by foreign secretary Sir Edward Grey, who declared on the eve of the declaration of war: "The lamps are going out all over Europe, we shall not see them lit again in our lifetime."

Lights Out is an invitation to everyone in the UK to turn their lights off tonight from 10pm until 11pm, leaving on a single light or candle for this shared moment of reflection.

Many companies and building have have pledged to dim their lights for an hour tonight, including the Houses of Parliament, BBC, Blackpool Tower and the Imperial War Museum North in Manchester.

Turner Prize winner Jeremy Deller has created an app featuring four films that he has been realising daily from the 1st Aug the last one will be realised tonight on the app during the hours of darkness and only for an hour.

Learn more about the Light Out campaign here