The ferry still runs every twelve minutes and costs two yuan. On the deck nobody looks at the skyline; they look at their phones, or at the water. This pier is the only place on the whole route where you can stand at the river's edge with nothing between you and it.

The waterworks has drawn from the Huangpu since 1883 and it is still working, so the promenade cannot cross it. Instead you are lifted onto a 550-metre steel walkway hung out over the water, which puts a fence and eight metres of air between you and the castellated brick you came to look at. You pass the building without ever being beside it.

New paving, new lighting, a security guard at each end and no shade anywhere. At three in the afternoon this is the safest and least occupied stretch of the entire route: twelve people in twenty minutes, nine of them walking through, none of them sitting down.

Coal ash was stored here for eighty years. The concrete cylinders are an art space now, with a café on the roof; the walls were never painted and still smell of cement dust when it rains. Inside the silo your own footsteps come back at you about half a second late.

Two blocks inland the promenade's vocabulary stops. Shops face the street, laundry crosses the lane, the ground floor is doing five jobs at once. This is where the people who serviced the mills lived, and it is the only place on the route where anyone asked us what we were doing.

The island is state land and mostly closed. The gate stands open, but there is a guard post beside it and a sign listing what may not be photographed. We walked eight hundred metres in and found nowhere to sit down.