If you are feeling moisture at the base of the walls, you need to fix the problem. And that is fixed from the outside. This is probably the reason the last owner wisely did not finish this part of the basement. If he did you would by now have a huge mold/mildew/rot problem. Finishing a basement that was not designed to be living space is often problematic. The exterior problem that is trapping water against the foundation maybe as simple as fixing the grading, removing gardens from around the permitter, and installing a system to carry the downspout water away from the foundation. Or it may involve excavation and waterproofing the exterior of the fountain and/or installing weeping drains around footings and draining to a sump pump. The prior owners of my house did the footing drains, sump pump and floated the basement floor. Rarely do I see actual water but during heavy rains and snow melt the sump pump is quite busy and I have to run a dehumidifier around the clock in non heating season. There is no way I would ever finish that basement. You can't waterproof the walls from the inside. Period.