Ildefons Cerdà laid out the Eixample in 1859 as a grid of octagonal blocks — each corner chamfered at forty-five degrees to give the trams a sweep and the pedestrians a small public plaza at every intersection. The trams are mostly gone. The chamfers, called xamfrans here, are still doing their job: every block-corner is a notch of building shadow that drops in across the sidewalk at a different hour than the long straight runs do. If you understand the geometry, you can walk a Cerdà grid at 2 PM in August almost entirely in shade.
The avenues run northwest–southeast and northeast–southwest, rotated 45° off cardinal. This means the sun, which travels east-to-west, never aligns with a street axis — it always rakes diagonally across. The Passeig de Gràcia and Carrer d’Aragó will have one side fully shaded and one fully sunny for most of the day, and the shaded side flips at noon. Within each block, the four xamfrans throw triangular shadows that fill in the gaps where the long building lines don’t reach. Walking the corner-to-corner diagonal — across a chamfer, down a sidewalk, across another chamfer — gets you most of the way across the Eixample without crossing a sun gap longer than a tram length.
The picks below are graded for that. They are short, because the grid block is short (113 meters per side, exactly), and because the Eixample in summer is best in small doses anyway. The Passeig de Gràcia picks pair with a Vermut stop; the Sant Antoni picks pair with the market. A caveat: the new superilla zones around Sant Antoni have removed some of the corner geometry by adding plantings and benches, which is good for everyone except the shade model. We’ve re-graded those manually.