What large antenna works best for a crystal radio?

[Jeffhs]

I've had two crystal sets in my life, one constructed on a piece of wood (as a Cub Scout project), the other a "Remco" crystal radio, both from the '60s. I used a 50' long wire antenna and was able to hear the local station (0.5 kW) three miles away on both sets. The Remco radio also picked up, to my surprise, after the local station had signed off for the night, a 5kW station from Cleveland. Never did hear any other Cleveland stations on either set; my having heard the 5kW station I mentioned must have been a fluke. I lived in an eastern Cleveland suburb (15 miles from downtown) at the time.