Arecibo was a radio telescope, like a satellite dish. The 'mirror' is a great big metal mesh hemisphere covering 18 acres of land in a mountain valley. It's n

Arecibo was a radio telescope, like a satellite dish. The 'mirror' is a great big metal mesh hemisphere covering 18 acres of land in a mountain valley. It's not an ideal museum location in and of itself because it's almost an hour drive out of the city across some not-sutiable-for-high-traffic mountain roads (see the beginning of the movie Contact for a pretty reasonable view of what the trip out and in is like). Presumably the idea is that if we go around building stuff and just abandoning it we're doing unnecessary harm to nature as well as creating hazardous environments, e.g. when people go in to take the scrap metal and have stuff collapse on them.