The Ponte Vecchio from book P1 of P3:
Vasari Corridor was like a broad serpent, snaking through the buildings, all the way from the Pitti Palace, across the Arno, into the heart of old Florence. The narrow, whitewashed passageway seemed to stretch for eternity, occasionally turning briefly left or right to avoid an obstacle, but always moving east … across the Arno. The sudden sound of voices echoed ahead of them in the corridor, and Sienna skidded to a stop. Langdon halted, too, and immediately placed a calm hand on her shoulder, motioning to a nearby viewing portal. Tourists down below. Langdon and Sienna moved to the portal and peered out, seeing that they were currently perched above the Ponte Vecchio—the medieval stone bridge that serves as a pedestrian walkway into the old city. Below them, the day’s first tourists were enjoying the market that has been held on the bridge since the 1400s. Today the vendors are mostly goldsmiths and jewelers, but that has not always been the case.