Mile 42.0 - Near mile mark 42, there a large culvert where the Little Monocacy empties into the Potomac. A great place to hunt pollywogs come early May. Between the towpath and the river is the remains of Doctor Boyd's homestead, built in the late 1700's, before the canal was started. It looks very similar to some of the lockhouse remains.
These pollywogs are plentiful and very easy to find. Climb down to the river level and look at all the shallow areas in the creek. On a good year, if there's lots of rain, you can find them in the canal too.