Since the 1960s, the works of the American artist Keith Sonnier have been focusing on artificial light - a material evoking a variety of associations with the aesthetics of advertisement and everyday life. The authors of the book at hand have set out to explore Sonnier's oeuvre, showing the artist's innovative way of blending light and architecture by means of two of his recent light installations: in cooperation with the Austrian-born architects Baumschlager & Eberle, Sonnier designed a light installation for a subterranean passage of the Munchner Ruck insurance company. Neon light in rich, deep colours fills the space, with the spatial qualities of light becoming perceptible in a highly sensual way. The installation for the parish church in Steyr-Resthof in Upper Austria, a new church building by the architects Riepl & Riepl, also inhabits a singular position in Sonnier's oeuvre to date. Sonnier's comprehensive concept turns the liturgical space into a light symbol, in the truest sense of the word elevating the aura of the building.