Help!

This is something that is driving me mad, and perhaps you can help me. Have a look at my little picture below – does that arched wall thing that my arrows point to have a real name?


It’s like a stone arched border/edging around a patio, but I am sure it has a proper architectural term for it, as opposed to me fudging around with arched balcony wall thing. I've been searching for this for ages, and it is beginning to send me loopy. Please forgive the bad illustration – but hey, I threw in a few potted plants!

Yours hopefully,
Jayne