Some parts and components of arcs
These are ready-to-use arch prefabs. It only needs to be repainted (unless you have my textures), also it's not optimized with null (but that's pretty easy to do, huh?)
They may be combined to receive the better-looking structures, but WARNING! those are high-polygonal prefabs (you wouldn't have lags using it gingerly but do not forget to optimize!)
Good luck & Have fun! x)