Romain Jacquet-Lagrèze is a French photographer who captures the dizzying heights and uncommon densities of Hong Kong. Inspired by "the geometry of the urban environment and the vivid lives it shelters," Jacquet-Lagrèze has not only captured the verticality of Hong Kong's built environment, but also compiled a new book, Vertical Horizon, "a photographic journey between the buildings of a relentlessly growing city." See more of Jacquet-Lagrèze's images, and read an excerpt from Vertical Horizon, after the break.