Hidden Rough-in??

My townhouse neighboors have a rough-in toilet in the basement or already have a bathroom. I on the other hand do not. I have carpet with a cushion pad over my basement slab so it's hard to tap around. I have an idea where one would be if I have one, but how do I locate it?

Thanks in advance for your advice / reply.

If this a tract house, the builder/developer should know. Usually, the pipes sticking out of the floor are a dead giveaway.

RE: Hidden Rough-in?

Thanks for the advice, I know to look for pipes...but I believe the rough-in was covered with at least a skim coat of concrete. I'm trying to locate it through the floor with the least ammount of destruction- any ideas??