Last week I was telling Billy about crystal radios, and I followed-up by digging up the one we built in London. I don't have my really good, HI-Z headphones, but even with fairly LO-Z cans, I could pull Vatican Radio's 1530 kHz signal out of the ether using just a Germanium diode, a coil, a variable cap, and my all-purpose end-fed wire antenna.
I live very close to Vatican City (see above), but I think their AM transmitter is out of town, to the North of Rome. I visited the Wiki on Vatican Radio. Very interesting. Turns out that the Jesuits run the radio stations. Go here for a virtual tour:
http://www.vaticanradio.org/museo_tecnico/it/gal_fot_24.asp It took me a few minutes to hook up the 4 parts of my crystal receiver; it seemed kind of fitting (and a bit eerie) to be rewarded with the faint sound of Gregorian chants.