Delve into the creepier side of Naples, starting off with a stroll through the Rione Sanità (closest metro stop: Cavour). The quarter started in ancient times as a place of burial, but today, it’s a lively place to people-watch, particularly at the Via dei Vergini street market, where you can find everything from lace curtains to chili peppers. Descend into the Catacombs of San Gaudioso ($11, also includes admission to the Catacombs of San Gennaro), ancient tombs reappropriated by seventeenth-century monks who drained and decapitated bodies before cementing their skulls—and sometimes spines—to the tufa walls. At the Cimitero delle Fontanelle, stand among the bones of some 40,000 souls, mostly paupers—plague and cholera victims from the seventeenth to nineteenth centuries. The cemetery was closed in 1969 over worries that it was promoting pagan worship, thanks to the popularity of praying to the bones, and only reopened full-time in 2010. Grab a life-restoring lunch at nearby Cantina del Gallo, a 113-year-old trattoria with a much more local feel—and better fritti and pizza—than famous Pizzeria Starita up the street. Head back underground with the guides at Napoli Sotterranea ($12.50), exploring caves and spooky water cisterns dating back to the fourth century B.C. and reused by Neapolitans in World War II as bomb shelters. Make sure to stop at the Ospedale delle Bambole, a tiny doll-hospital stuffed with oddly spooky dolls. At the Cappella Sansevero ($9.50), don’t miss the eighteenth-century “anatomical machines” downstairs, two skeletons that appear to have mysteriously kept their arteries and veins intact. Shake off the day’s goosebumps with dinner at Palazzo Petrucci, a Michelin-starred restaurant (one of just two in Naples) that’s the most elegant option in the centro storico. Finally, wind down the day with a cocktail at Caffè Arabo ($7–8), watching hip, grungy students smoke, kiss, and gossip on Piazza Bellini.