Castle Turrets Need Circles - A Simple Method That Works A square castle with round turrets looks twice as grand, and the turrets are the easy part. A diameter 9 or 11 circle at each corner, built a few layers taller than the walls, gives you that classic fortress silhouette. Overlap the turret circle into the corner so about a quarter of it sits inside the wall line - the join disappears and the walls look like they flow into the tower. Cap each turret with a shrinking-circle cone roof and a flag. Arrow slits are just gaps: leave a one-block hole every three layers, alternating sides, and the turret is functional as well as pretty. Plan your own circle here: CircleCraftLab