...Jodrell Bank. The lovely Lovell radio telescope sitting in the Cheshire countryside has won the BBC unsung landmarks competition. I think it is a very deserved winner and more people should appreciate the beauty of astronomical instrumentation. There are some great telescopes around the world that look fantastic and are truely epic pieces of engineering. You've got things like the Gemini and Keck telescopes, with huge 8-10 m mirrors that had to be transported to altitudes of a few km at the top of mountains - in fact at the Gemini South site in the Chilean Andes they had to blow the top of a mountain to flatten it out! You've got the Arecibo radio telescope which is 305 m across and built in a huge sinkhole in Puerto Rica. These are amazing instruments doing cutting edge science. I suggest visiting their respective websites to check how good these thing look to. Older smaller telescopes also look pretty damn cool and beautiful too and are incredible demonstrations of precision engineering from 100s of years ago - check out the pictures of the Radcliffe and Joynson telescopes which I got to use as an undergraduate at the University of London Observatory.
Update: It's been pointed out to me that I missed our our own beloved GEO600 in my speil about wondorous astronomical instrumentation. This was an oversite on my part. I should also give a nod to our maybe slightly more impressive and larger (well it eats a bit too much ;) ) American cousin LIGO.