More than 1, 500 historic buildings dot the downtown area, and because the city was built atop a drained lake bed, some edifices , like the gravity-defying Ex-Teresa museum, a former 17th-century convent, are teetering like there is no tomorrow.

BBC: Mexico City: More than a stopover

Once I was in bed again, a kind of black-hole gravity held me there.

NEWYORKER: The Reptile Garden