Up to ground level via an aggressively inclined and narrow stone spiral stairwell, so steep a defibrillator was blinking and ready at the top. Into the heat and sun again, les Catacombes exit on a street several blocks from the entrance.

Walking back to Denfert-Rochereau to ride Line 6 to the aptly-named Charles de Gaulle - Étoile ("star"), these wedged buildings on the corner of Rue Rémy Dumoncel and Rue Montbrun caught my eye. Paris' scrambled, fragmented road network means most buildings are unusual shapes, which makes for confused sight lines and an odd sense of what's parallel.