Secret underground tunnels in your basement?

Just to put this post into context, I watched a report on TV about KB Home selling homes in an Arlington neighborhood built on top of a former target practice site used by Navy pilots during World War II. The buyers were not told about that, so they were very unhappy because their kids playing in the back yard found unexplosed bombs. The Army Corps of Engineers later came to clean the place and dug up more than 150 unexploded practice bombs.

Now with that being said, here's a bit of wishful thinking on my part. This story made me think... what if your house was built on top of an abandoned secret underground base? Is that even possible, did it ever happen before? Time to dig your basement, you never know what you may find. LOL Just imagine you could walk in tunnels traveling under the entire city, and not even your neighbors would be aware such a thing exists.

Or maybe you did discover secret tunnels in your back yard and you don't want to share it with us?

Depends on what the tunnels are for. Secret Base, shelter, storage, hideyhole. If anyone spent signigicat resources on sub-terranian dwellings it would be rather obvious with the extra plumbing, and electrical