Paris: 11th arrondissement
The 11th arrondissement of Paris gives you the chance to do maths. Its overall shape is quadrilateral, with three of its vertices at the Place de la Nation, Place de la République and Place de la Bastille, respectively. If it’s figures you’re after, how about the considerable number of metro lines that cross the district? As for the practical application of elementary rules and theories, that is left to the cabinetmakers, incapable of making lop-sided furniture; the silversmiths, specialists in working in millimetres; and the harpsichord-makers, who are not afraid of highly technical resonance calculations.