Trees in walls

Walked close to Bath recently, and a field boundary had a lovely old stone wall, that had been swallowed by trees.  I wish I had taken a photo, because it was quite something to behold.  Roots wrapped in and out along the entire stretch adding height to the wall.  Somewhat sad that the wall wasn't visible, but a great result, that got me thinking that perhaps you could do this with a cheaper medium, perhaps gabions or some other retainer and a friendly fill.  Anyhow, I'm thinking about building with gabions, and filling them with on-site chalk.  I know Yews grow almost fine in pure chalk, perhaps I could just plant up a structure for the future.

Anyone tried anything like this?