Why it looks like this

The waffle-like grid of octagons is the Eixample — "the expansion" — designed by engineer Ildefons Cerdà in 1859, when Barcelona finally pulled down its medieval walls. Every block is a square of about 113 metres with its corners cut off. Those cut corners (xamfrans) let horse trams turn easily — and today they make every crossing feel like a small plaza.

The tangled streets near the harbour are everything the walls once held — the Gothic Quarter, two thousand years of streets with no plan at all. One city shows both extremes of city-making, and the line between them is a single street: La Rambla.