Jean-Jacques Lequeu does in fact hide behind the most enigmatic and controversial smile in the history of art, writes Philippe Duboy in a book that is one of the most tantalizing examples of architectural investigation ever produced. It is an extraordinary compilation - part speculative biography, part meticulous research, with hundreds of intriguing drawings, many in color - that unravels the mystery of this eighteenth-century maverick artist whose drawings have established him variously as a visionary architect associated with Boullee and Ledoux, forerunner of surrealism, and inventor of bad taste. Lequeu's architectural drawings from the legendary portfolios Architecture civile and Nouvelle methode are presented here in their entirety, along with his Lewd Figures, perhaps the oddest feature of the whole collection. The drawings are accompanied by long captions, misspelt and ungrammatical, but written in a flawless bureaucratic hand. The artist's marginalia provide insights into his visions, which seem dominated by an obsession with petrified forms and a recurring preoccupation with sex. Interleaved with the drawings are curious autobiographical papers. And it is here that Duboy's investigation of Lequeu begins to reveal strange clues. He discovers that Lequeu was not an architect at all but a government bureaucrat, a draftsman who ended up living in a brothel. Between the brothel and the obscure office from which he was eventually fired, he produced his encyclopedia of the universe - bizarre portraits of nuns baring their breasts and other lewd figures, and architectural fantasies of vast imaginary cities. Duboy takes his study further, into the realm of Charles Fourier andhis brother-in-law Anthelme Brillat-Savarin and from there to the world of the dadaists, surrealists, and futurists, particularly the circles of Marcel Duchamp and Le Corbusier. He suggests that Duchamp and Raymond Rousell tampered with the Lequeu drawings to concoct a character and oeuvre even more puzzling. There are glimpses of Duchamp's convolutions of mind that will stir a reassessment of his work. Duchamp emerges here, for the first time, as an intrepid and unwavering despiser of Le Corbusier. Twentieth-century reputations are as much at stake in this study as those of the eighteenth-century artist, notes Robin Middleton. Philippe Duboy is Professor of the History of Cities, Paris-Belleville School of Architecture.