Me too! In the early 1970s we used to access the storm sewers in our town of Rutherford, NJ and could walk all the way out into the Meadowlands ( this was before they built the sports complex and Giants Stadium). Probably was well over a mile. It just curls my hair to think of it now. We got caught when a cop heard us talking while we were at a sewer grate. He bent down to take a look, saw us and then his hat fell off. My brother’s friend grabbed it and took off laughing. Within a couple days they had put a big gate over where we used to walk in!

We used to play in abandoned houses/buildings and on the top of a mile-long stretch of abandoned elevated train stations.

Our parents especially hated the second one but that just meant that we'd duck a little lower while passing through the portion of it that overlooked our street.