50 Cities 50 Traces is an international art and peace project to commemorate the 50th anniversary of the Treaty on the Non-Proliferation of Nuclear Weapons signed by the nuclear-weapon states the USA, the Soviet Union and Great Britain in 1968. The exhibition will be open on weekdays from 12pm until 6pm. There will be a series of 30-minute lunchtime talks from notable speakers around nuclear disarmament and related themes.