Arecibo Observatory
The nerd highlight of my trip to Puerto Rico was visiting
the world's largest radio telescope dish, at
Arecibo Observatory, technically
the National Astronomy and Ionosphere Center, run by Cornell for NSF.
They took a whole valley, rounded it out a bit, and covered it in
aluminum mesh.
It's big.
Really big.
So big you need an
aerial view to really see the whole thing.
(1000 feet across, with the
transponder 500 feet above the dish.)
Plus, they move the transponder in the middle every half hour or so! I had a blast.
The dish has appeared in two major movies,
Goldeneye, in which it played a secret Russian radio transmitter
in Cuba, and
Contact, in which it played itself.
My best souvenir was a
bank machine receipt that says "ATM: Radio Telescopio" on it.