New York City in the summer is notorious for its uncomfortable heat and sticky humidity. Tourists in Midtown sag together,  pushing past each other in a sweaty August frenzy. Taxi exhaust clogs the air, the sun tries hopelessly to pierce through the smog and Manhattan swelters — a tired, miserable haze. There is no reprieve beneath the sidewalk. Steamy subway platforms seem to breathe, and the metal cars push columns of air even hotter and denser than the oppressive heat in Times Square.