Why it looks like this

Tenochtitlan, founded on an island in Lake Texcoco in 1325, was one of the largest cities in the world when the Spanish destroyed it in 1521 — and then rebuilt their capital directly on its ruins. The Zócalo covers the Aztec ceremonial centre, and major streets like Calzada de Tlalpan still trace the causeways that once crossed the lake.

The lake was drained over centuries, and the city pays for it daily: the soft lakebed has let the historic centre sink on the order of nine metres, tilting churches and swallowing foundations, while the metropolis spreads across the entire basin where the water used to be.