Delhi

Delhi's secret is vertical. This is not one city but a stack of at least eight, each built by a new power beside or on top of the last, and the stack is still legible if you know where to stand. I gave my first days to the strata. In Mehrauli, the oldest layer: the Qutb Minar rising seventy-three metres in fluted red sandstone bands, begun in the 1190s as victory-in-masonry, its courtyard holding a still-older riddle, the Iron Pillar, sixteen centuries old and famously unrusted, metallurgists' pilgrimage and picnic backdrop at once. Around it, the Mehrauli Archaeological Park scatters seven hundred years of tombs, stepwells and mosques through a forest where teenagers rehearse dance videos among sultans. South and east, Tughlaqabad's cyclopean ruined ramparts run for kilometres, cursed, the story goes, by a saint whose words Delhiites still quote when the city misbehaves: ya rahe ujjar, ya base gujjar. And in Nizamuddin, the Mughal layer opens with

Humayun's Tomb: the first great garden-tomb of the dynasty, red sandstone and white marble in a charbagh of ordered paradise, built by a grieving widow a full century before her descendant answered it in white at Agra. Standing on its plinth at dawn, parakeets auditing the dome, I could see the Taj being rehearsed.