The Imperial Bridge

Tal Mallan, City of Walls.  Two rivers run through it, both are wide and tempestuous by the time they reach the city and they force their way through to the sea like bullies in a bar.  There are high and wide levees in the richer parts of the city; there are streets that function as flood-plains and houses that are regularly filled with mud and water in the poorer parts.  There hasn't yet been a winter where people haven't died, either because the melt-water caused freezing floods or because the icing of the rivers split the barricades set up to hold them back.  Their names were Twivix and Lernal, and they were named after fractious twins in a local legend.
I was on the Imperial bridge which crosses the Twivix, having been walking for half the night.  I'd been woken by noises; the scraping of chitinous claws against the fabric of reality, the sounds of frail curtains tearing, and the heavy, wet breathing of things that shouldn't have lungs, shouldn't have dragged themselves out from the depths, things that are jealous of the brightness and the warmth of the life they dimly perceive just out of reach.  I'd been eating haruspice the evening before, Tal Mallan's most important spice, the one you have to cross the seven walls to find.  The one that is policed and regulated so fiercely that almost no-one will attempt to smuggle it out or deal in it.  The one that allows a limited glimpse of the future and demands payment by later on showing you the present as it really is.
I shivered, my skin was still clammy and I could taste the aniseedy, cinammony headiness of the haruspice again.  It was slowly seeping out of my pores, and I knew that I should be alone, washing regularly, not contaminating the outside world with it, but I couldn't face going back into that house and seeing the things on the other side of the walls; well, the other side if you could count your dimensions correctly.  I leaned on the metal railing that edged the Imperial bridge and looked down on the Twivix.
The water was foaming and racing, building up momentum as it approached the shallow falls, a twenty-yard drop that coincided, not at all coincidentally, with the second of the seven walls.  You could try and climb the wall, persuade the gatekeepers that you should be allowed passage, or try and find a wall up sixty feet of angry waterfall.  Or you could turn back and learn some common sense.
I had walked out from the fifth wall to here and I could get back again; my badge of office would get me through the third and fourth gates, and I could command the guardians of the fifth gate though it was painful and difficult.  Which was, of course, why I couldn't venture through the sixth or seventh gates, the guardians would seize me and consume my soul, slowly over the years, luxuriating in my pain and prolonging my death.
The Imperial bridge was a filigree structure of bronze, tantalum and carbon-fibre that glittered in the afternoon sunlight and was like a bridge of white fire in the stronger morning sunlight.  Here, just after dawn, the bridge was drinking in the light as the sun rose, and I could feel it getting warm beneath my fingers.  I estimated that I had perhaps another hour before it was too hot to stand on, and perhaps an hour and a half before the bridge was lethal to approach.  But here, above the Twivix, surrounded by air, surmounting water, embracing arising fire, and with pockets filled with grave-earth, I could direct the haruspice hangover, free myself from the visions of what really was and wander astrally for a time, seeing what was to come.
Of course, as is always the case when I've come prepared, the only vision of the future I could see was me leaving the bridge in half-an-hour's time, walking calmly down the steps on the left-bank and heading for my favourite coffee-house where I would buy a coffee and a buttery, flaky pastry.
I shook suddenly, leaving the vision behind.  The water beneath me roared hungrily, and I stared into it, wondering what had shocked me.
Then I realised: my favourite coffee-house had burned down three days earlier during a riot in the second wall district.  So what on earth was the vision telling me?