This is one of the channels of the water system in the garden, which I thought was fascinating, although I am told is a very old way of channeling water.

The water starts on the level above (pictured below) and flows into channels like this which ultimately deposit the water into a fountain on the last of three levels in the garden. Unfortunately, it was all turned off when we were there for repair, as Tim said the main fountain had been overflowing. Another reason, one among many, to return to this lovely garden!

The first stage of the water system: