An idea passes like a delicate thread from the scientific Enlightenment through Romanticism and the Victorian age: that of a veil behind which true knowledge may be found by those able to draw it aside. The Thin Veil of London is a journey into the worlds of Faery and science, madness and ecstasy, and what Arthur Machen (1863-1947) called 'the eternal beauty hidden beneath the crust of common and commonplace things; hidden and yet burning and glowing continually if you care to look with purged eyes'. The ideas that informed his writing at the turn of the last century lie at the brink of Modernism but look back to both ancient horrors and ancient truths. Yearning for transcendence, Machen articulates not only the anxieties of his age but also a deep tradition in which we still find ourselves immersed at the beginning of the twenty-first century. This book emerged from tours of Holborn and Bloomsbury performed in 2013 in collaboration with the Museum of London to mark Machen's 150th birthday.