Boni, a simple way to start out might be to just make some elongated steps (there are tutorials on this starting with just a cube), then use the Simple Deform modifier in Bend mode to bend them 180 degrees. Just make sure you have enough segments so that they bend nicely. From there, you can add the stage and platform as separate objects. This way, the whole thing is very easy to unwrap and texture. I don't know how realistic you need it. If you need ultra-realism which hold up in close up rendering, then I'd recommend using actual blocks for the stones like Lobo suggested. However, you can get a lot of mileage for this kind of thing using textures and displacement or normal maps too.

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