yeah i found a couple of those, they are nice for getting some free tracks and fences if you really want them, or just starting your own minecart system
They're all over. Look at the worldmap and flip it to cavern, you'll see abandoned mines all over. Most are full of cave spider spawners though.
![[Image: 20110917040911.png]](http://img148.imageshack.us/img148/6557/20110917040911.png)
![[Image: 20110917040905.png]](http://img101.imageshack.us/img101/4127/20110917040905.png)
![[Image: 20110917040907.png]](http://img14.imageshack.us/img14/9569/20110917040907.png)