NHM: diatom tower HDR

Today I went for a little explore with a colleague: I asked him if he knew of any behind-the-scenes or "secret" places which we could visit, and he took me up to the mostly unused central tower which used to house the diatom collection.

Most of the museum's towers are (pretty much) off-limits due to the fact that they each have only a single staircase for access, so would be inescapable if a fire blocked that staircase. Some of the towers are used for storage, but mostly they are just abandoned for the time being. It seems such a shame: from the outside, they seem such a prominent part of the museum, and it seems (to me) as though they ought to house important offices, labs, or collections...
I don't see why they don't just have escape ladders from the rooftops, or fire-poles!

Anyway, they are actually quite creepy: many haven't been cleared out so look just like offices, but for the dust, empty water bottles, &c. It is as though they're in use, but the people have vaporised.

This staircase leads from the fourth floor up to the very top of the tower, and seemed particularly creepy, creaky, and isolated. I was up for exploring when we started, but going up these stairs from an already very isolated level seemed slightly unappealing.