This Sims 3 tutorial will show you how to build a proper fountain above ground without all those very thick, large, ugly foundation borders around them. This sadly does not work with curves.
Draw a Foundation.
Enable “constrainfloorelevation true” in the cheat console, and select the fountain tool. Drag the fountain across the foundation. Do NOT select a curve, as it will not work.
Flatten the terrain around the foundation.
This will cause the walls to raise up to the standard wall wall height. Resize the height fountain to any height you wish. An appropriate height here would be the same as a foundation.
Drag the “Level” tool from the foundation to the fountain, and it will be the same height. Then, delete the foundation if you no longer need it.
And that’s it!