I opened my eyes to a world without colour. The same world I’d always known, as long as memory allowed. I pushed back my blanket and rolled it up as tight as it would go before slipping it into my rucksack. In the hazy corridor visible through the doorway on the far side of the room, I could see people slowly moving past, heads down, a heavy silence hanging low over them like a cover of dark, unyielding clouds. They were going up, always up.

I moved to the doorway and peered past the crowd, out through a grimy, half-open window and into open air. Moving fowards, I pushed through a group of three and went to stand at it. I had seen the sight thousands of times before, yet each morning something always compelled me to step up to the windows and look again. A clothes-line hung from one side of the Tower to the other, over the yawning gap at the centre of the world, or at least the world we knew.

And, oh, what a world it was. Greyscale, hazy, with a fifteen-by-fifteen metre core of abyss enclosed by concrete walls of endless height interrupted by an infinite chaotic array of glass windows and inset balconies, and the very occasional door out into nothing, the mere presence of which suggested something I preferred not to dwell on.

I craned my neck and looked up. Somewhere up there, amidst the gathering grey that obscured all hints of what we might be climbing to, light shone. By the time it reached this far down it was pallid and faint, but it never wavered. Night, like colour, was a thing we knew of but had never seen; sleep came only when our eyes drooped and our legs would go no further, morning at the whims of restless chance.

I looked down. Darkness met my gaze. As the concrete walls stretched low the way we'd come, shadows gathered and eventually engulfed everything. Just as we couldn't see what we were climbing towards, neither could we see what we had left behind ― if there was a bottom or if the world kept going forever. And that shadow... no matter how far or fast I climbed, it was always just as close.

I felt, sometimes, as I looked into it, that it was looking back at me, into me. I had spent long hours wondering if it was just an illusion of the world, if the people down there saw everything the same as I did, or if as I climbed the darkness followed me and consumed all in its path. I was quite sure it was the former, quite sure that it was simply a law of the world that each person should always live in the same pale light, but I was never brave enough to test that theory. To turn back.

No one ever turned back. No one ever moved down. Not by choice.

Such thoughts, I decided, had held me at that window long enough. There were people who lingered too long on one floor and became unable to move on, who claimed rooms to call their own homes and were stuck forever in stasis. The frozen, we called them. They lived out the same days over and over again, in the same place, going nowhere. It was a fate worse than descent, and some said if you loitered too long the walls would call to you like sirens on the rocks, beg you to stay, and then you would be lost.

I stepped away from the window and started my climb for the day. A faster walker than most, I moved along the outside of the steady trudging stream of figures, my rucksack strapped tightly about my chest and waist. Most of what I carried was clothing and blankets ― there wasn't much to be said for hauling food around in the Tower. Every floor had an endless yet somehow short supply, so that we were always hungry but never starving. The only nutrition I carried with me was a large plastic bottle for water, refilled at the taps that could be found along the hallways every now and then.

The strange thing about life in the Tower was how it all seemed to weigh on you so strongly, and yet it never became too much. Even the frozen had not stayed still because their will was broken, or because settled life had seemed more appealing to them. They had stayed because the walls had sung to them, and the song was something you couldn't avoid once it had you in its thrall.

Though each day was the same as the last, though nothing seemed to change much and for all I knew we might be climbing the same hundred or so floors over again each day, though the world was all grey and haze, though every night passed by dreamless, and though in the end all friends and family we had ever known befell some trap or other, be it plague, descent, or terrible stasis, the climb never seemed impossible. Perhaps it was because we knew it was all there was, because in lieu of all other goals we marched to the one we could hope of. Or perhaps it was simply because that is how people are, in this world.

But there were times when I did wonder: if this is all the world is, how do we know of day and night? How do we know of colour and dreams and of all the things beyond this drear eternal march?

And those were the times when I paused and looked into the hallways leading out, away from the centre of the Tower. Long, empty corridors lined with doors, stretching like fingers out from the repeating halls that wrapped about the centre again and again, rising so slowly. Corridors that led who knows where? Corridors we all knew not to look at, whose ends were, as the depths, all wrapped in shadow. Whose insidious whispers sought to tempt us from the path up towards that light we coveted and endlessly, fruitlessly pursued like moths against a window.

And those corridors... in those moments, they beckoned.