I've been inspired by the guy who had pipes outside his house he didn't know what they were there for!
In my basement (mid-70's construction) there are three places in the basement floor that drain water flow into. Presumably they're all joined somewhere under the basement and lead to the county sewer system. In my house the pipes coming out of the concrete are cast iron (or some kind of big thick black metal) for a foot or so above the floor and the ABS plastic drain pipes are coupled on.
But in one place (roughly in the middle of the house near the chimney) there's some other mysterious pipes coming up through the floor. They look like cast iron to me. One is like an upside-down U, about a foot high and two feet long, both ends going into the concrete. The other looks like maybe is in there as a "future" drain, it's located pretty much right under a vertical duct where maybe a drain stack might be put in.
The house was originally built with an oil-burning furnace, but was converted to electrical heating many years ago. Physically the oil tank was located outside the house near the attached garage. I think the original furnace was roughly where all three of these mystery pipes were.
Any ideas? Maybe it's just conventional to put a drain near where the furnace goes (for future dehumidifier?) What about that funny U-shape pipe - maybe for protection, but why would you worry about physically protecting the oil-burning furnace, it's not like there are forklifts or delivery trucks driving around in the basement...