In its shopfronts cashmere sweaters the colors of macaroons. Behind their digicodes its reposing hameaux. In its ballot boxes three out of every four votes for Sarkozy. Hidden in their Maseratis its children dressed in black. The sixteenth arrondissement of Paris is a peninsula between the Bois de Boulogne (which belongs to it) and the Seine; there is the slight feeling of a border crossing, of breaching a feeble forcefield, upon entering or leaving. One can find here the works of Perret, Sauvage and, soon, Gehry, but it is the section of the Earth’s surface with the greatest concentration of buildings by Hector Guimard (1867-1942). The seizième is to Guimard as Oak Park is to Frank Lloyd Wright, except that it contains works from all periods of the architect’s career, from 1891 to 1927. Along the way one passes other buildings which support the contention, inherently arguable and worth arguing, that the sixteenth is the most architecturally interesting arrondissement. Annexed to the city in 1860, the seizième grew up in what we might call, with light apologies to Robert Caro, The Years of Hector Guimard, a complex, under-appreciated and richly contested period in the history of modern architecture. A new eclecticism began to rebel against the last moments of a played-out Haussmannization. Many modernisms were in play. Art Nouveau, which seems barely able to contain Guimard’s work, let alone the output of the entire period, may now seem the stuff of coffee table books, a particularly beautiful dead end, a fashion, a decorative style, but its surviving remnants hint of an influence more spiritual than physical.