No New England episode, huh. Well. I guess I'm not wanted! Anyway, too late for my yard, it's wildlife friendly already! :) Mary

LOL...I first read kelley's description as divots that were about 20 to 25 inches deep! Whew, my advice was to pack your suitcases and run! Inch deep, conically shaped pits certainly fit the description of ant lions at work. Any chance of a picture of these divots?

We put in a patio as well; we ran natural gas and electricity out to it too. We can't see your whole yard, but it looks like you don't have a lot of room; I would hardscape (slate, fieldstone, pavers, not concrete) or put a deck on that entire left side of the picture. It looks like you have a small (?) area of grass/dirt on the right side, where the basement door is. I'd till that up and plant a garden of some kind; veggies, herbs, flowers, a mix? Oh, and a discovery that may change my life; I will never again bother with raking and seeding a large area of lawn. Patches, sure. But when we had the patio put in, they put sod around it. It was surprisingly affordable for our small space, and that instant, thick green lawn was wonderful. So, that's my advice to you. Sod. :-) The picture is the last day of installation; it's the only one I have from above.

Alright, y'all! We excavated it and I think we have an old septic tank on our hands. However, we think it pre-dates our house, which was built in the 40s. The pipe that fed the tank at one point comes from the opposite direction of our home, and we found what appears to be evidence of an old foundation further back on our property. Very cool! My husband hacked up the bottom and sides of it with an axe, and we filled it in with several cubic yards of sandy loam and large rocks, watering and tamping between each layer. This thing is solid now, and I'm glad that no one fell through the "roof," as it was composed completely of dirt and interwoven roots. The previous homeowner definitely knew about it, as a large paver was placed over the small hole that we initially discovered (eye roll). I'll attach photos and you guys can tell us if you think it's a cistern or septic tank. I love this thread, by the way! Thanks for everyone's help!