It looks like a cross between a castle and a mechanical spider; if I had been shown an uncaptioned picture, I would have been convinced it was a movie prop.
But it's real: Cruquius, the largest single-cylinder steam engine ever built, a Cornish Engine far from Cornwall. And it's big: the primary piston is 144" in diameter. On the official site, there's a page with a video that follows a reporter inside the main cylinder.
Restored but not under steam (the boilers are long gone), nowadays, the engine is moved by hydraulics; but move it does and it's an image you're not likely to forget.
What did it do for a living? Why, it helped drain the Netherlands!