We are going to walk the river, south to north, across seven crossings. This walk is different from the others: the things you are looking at are far away, so you will be standing still more and walking less. Bridges are windy, so bring a layer. And if you can choose the time, come after four in the afternoon — the light comes down the river from behind you. A longer second track, Go Deeper, sits behind some of the stops. It is not for the bridges — the wind and the view both want your attention. Keep it for the way home, when the water is behind you. About an hour. Start on the blue bridge, five minutes south of the big gate.

Start on the blue bridge. It is about five minutes south of Kaminarimon if you follow the water. Walk out to the middle of it, stop, put your back to the traffic and face north — upstream, towards the temple you have just come from. Here is what is in front of you. A wide, flat, grey-green river moving slowly. A concrete wall running down both banks. And a line of bridges going away from you into the distance. Count them. On an ordinary day you will see three, and on a clear one, four. Every single one is a different shape, and every single one is a different colour. None of that is an accident, and working out why is what this walk is for. Now look back at the bank you came from, at the western end of this bridge. Set back from the road there is a small hall in dark wood, easy to mistake for an office. That is Komagatado, and the bridge is named after the hall, not the hall after the bridge. By the temple's own account, this is where the whole thing began. In the seventh century, two fishermen brothers pulled a small golden figure of Kannon out of this river in their net. They put it back in the water. It came up again. That is a story, not a documented event — the temple's account of its own origin. But hold on to the shape of it. Two working men, a net, and a river that fed a village. The pilgrims, the shopping street, the theatres, the crowds and the giant lantern all arrived afterwards, because of the water first and the temple second. Asakusa faces the temple today. For most of its life it faced this. Walk north along the bank, about five minutes, to the big red one. That is where the argument happened.

Walk out to the middle of the red bridge and stop. Face south, back the way you came. This is Azumabashi, finished in 1931 — the bridge in almost every photograph of Asakusa ever taken. Before you look at the view, look up, and notice there is nothing there: no arch, no truss, no cables. This bridge carries all three of its steel arches entirely beneath the roadway — the opposite answer to the bridge you were just standing on. Now look south, down the water. You can see three bridges at once from here, and no two of them are the same colour. None of that is decoration, and the reason starts less than a century ago, with why this particular bridge had to be rebuilt at all. On the first of September 1923, an earthquake struck at lunchtime, and the fires that followed burned for two days. Most of eastern Tokyo was wooden and packed tight, and it went. The wooden bridge on this spot went too. That is the detail worth stopping on: people ran to the bridges. A bridge is the obvious place to go when the ground behind you is burning — flat, open, and it leads out. Very large numbers had that idea at the same moment, on timber structures, over water they could not reach. The bridges did not save them. Along this river, in several places, the bridges were the trap. Stay where you are and look east, across to the far bank. There is a black building over there, and something gold lying down beside it. That is the next stop, and you can see it from here.