What was so impressive about all that was the level of technical ingenuity that went into it. I thought this one was pretty cool as well:

https://en.m.wikipedia.org/wiki/The_Thing_(listening_device)

If my memory is still holding up I think they also pulled off another passive bug in a State Department conference room one time but I can’t remember enough about it to find a reference online. It was the same deal though - short piece of wire attenuated to a certain frequency and they’d illuminate it with a microwave truck parked on the street.