An unassuming set of metal stairs, yes? Well, sorta. But they are part of one of the first ever attempts to build a repository to keep stuff *forever*. It's the first Public Record Office building in the UK, now part of Kings College London library. Most of the original furniture is swept away by the needs of a modern library but they have preserved a couple of corners. Here you can see the building is largely metal in its fittings (metal and slate in the strongrooms, in fact). They were trying to design a fireproof place where the oldest documents in the country could be safe. It's also not solid, full of grilles (including the mezzanine floor where these steps lead): the idea was to avoid creating mould pockets (get that air circulating), and let any dust fall down to the ground where it could be regularly swept up. Dust is a preservation enemy too, in a more subtle way than fire.
We wouldn't do it like this now, but I'm so glad I had the chance to get in to see it last Open House London.