Good idea to let the roots do the work. For a cellar wall you want something that won’t gnaw through stone, but will hold tight. Clematis armandii or Virginia creeper are gentle climbers that spread fine roots along the masonry without breaking it. If you prefer a more robust root system, blackberries or raspberry can work, but they’ll produce a lot of fruit and vines that need trimming. Ivy is a classic; it’s very fast and will cover cracks, but it can become invasive if you let it run wild. Plant a mix of a few of these, keep the soil moist but not soggy, and you’ll have a living, breathing seal that’s easier to maintain than a slab of concrete. And remember, never let them get a head start on the cellar floor – you don’t want a green carpet you can’t see through.