I'm just wondering if there are other folks out there who have found artifacts or other things underground in their yards that they weren't sure as to what they were or if they did know what they were, didn't expect to find such a thing or things in their yard.

While rototilling a number of years ago for a garden area in my back yard, I came upon a square cement slab that I didn't know was there. When I lifted the slab up, I uncovered the end of an approximately 6 inch in diameter pipe. Upon dropping a rock in the pipe, I could here the rock take a long time, like three or four seconds to hit the bottom. To this day, I don't know what that pipe is for.

Has anyone got any ideas? I don't think that it is an old cistern because I don't think it would be that deep. Although, I could be incorrect about that. Maybe it is the shaft to an old well? Don't know.

What interesting thing or things have you found underground in your yard?