We are planning a root cellar for vegetables, potatoes, and so on

We have a lot of sand.. it will (hopefully) all seep away. There is also a drainage channel.

Beautiful! I also dream of a [Erdkeller] :) Unfortunately, we don't have any old vaults to convert. I'm curious how things will be stored in there.

Our earth cellar is now almost finished. Visually already a real gem. The door is still missing and inside we want to install shelves. Before… After..

There are also ready-made kits for earth cellars for lazy people, where only an excavator with a lifting capacity of at least 1.5 tons is needed for the "assembly." It then sits really deep in the ground. One model is, for example, Cellaterra. It costs around €5000.
Of course, it's nowhere near as nice as Steffi33's :)

Are there also photos from the inside?

Yes.. they exist.. Compared to the outside, quite small ;) We want to use the ring in the ground for potatoes. Before… after..