Many fundamental principles of modern physics, taught in schools and universities all around the world, were conceived or discovered in Leiden. From bending light and the discovery of superconductivity to fundamental contributions to the theory of relativity and quantum mechanics. To show the people of Leiden what has sprung from their city, some of these discoveries are displayed on walls in the city centre. Inspired by TEGEN-BEELD Foundation's fantastic wall poems, these have taken the form of 'wall formulas.'

Photo of one of the Leiden Wall Formulas: The discovery of electron spin by Leiden physics students Samuel Goudsmit and George Uhlenbeck, on a wall at 't Gerecht in Leiden.