The recent failure of two support cables at the Arecibo Observatory in Puerto Rico has destabilized the structure such that it cannot be repaired without placing construction workers at significant risk.
Took my wife to see it when we were in Puerto Rico on vacation about 20 years ago. She humored me even though it was almost a 2 hour drive each way (it helped that the countryside around it is absolutely gorgeous) but even she was impressed when she saw it. I can still remember the sorta weird background noise when were walking around the observation area at edge of the dish. I think I might even have the t-shirt I bought at the gift shop shoved in a drawer somewhere.