The colonial old city, laid out by the Spanish on top of the Aztec capital and now a UNESCO World Heritage Site. Around 1,500 historic buildings sit in a grid centred on the Zócalo, including the Cathedral, the Templo Mayor, and the Palacio Nacional. The streets immediately west of the Zócalo are pedestrianised and full of life by day; many close around dusk. Easy to walk in a day, but a week wouldn't exhaust it.
Centro Histórico
UNESCO colonial grid built over the Aztec capital, endlessly walkable