To build a waterfall that resembles the type of waterfall you would see pouring out of the ancient stone walls of Roman baths, you need to first find or purchase at least twenty or more rounded stone boulders that are slightly flat on top.
Your first step is to build a stone and mortar brick wall by laying these stones on top of each other. This wall does not have to be perfect. It should almost look like a ceremonial stacking of stones. Be sure to stack the stones so that about three quarters of the way up the wall you have left room to insert a one inch copper pipe. This pipe is inserted into the wall along with PVC tubing that can either be attached to an external pump (hidden behind it) or to a submersible pump. The copper pipe, which oxidizes with time, also looks nice if it is sawed of at an angle to look like a spout.
When you turn on the pump, the water should splash out of the side of the wall. If you want to create the look of moss covered ancient walls in a hurry, try smearing yogurt over the new rocks. This will age them and encourage plant growth quite quickly.
Another easy type of fountain o make is the flat ledge fountain. To create this fountain you will have to acquire at least thirty broken pieces of flat stone slate. Make sure that you have one piece of slate that is at least three times as large as the others. The idea is that this piece of slate will extend laterally out into the pond.
Build a support for this slate by stacking cinder blocks at the desired distance out towards the center of the pond. Stack the largest piece of slate so that it is leveled and supported by both the edge of the pond and the cinder blocks.
You can use an external pump for this waterfall and hide it beneath the slate stone staircase or you can thread PVC through the rocks and use a submersible pump.
Build a supporting wall of cinder blocks a foot or two away from the pond. Now stack the flat pieces of slate on top of each other, using the larger pieces on the bottom and the smaller pieces on top to create a variegated staircase effect. The result will be a lovely cascading flow you can enjoy for years